diff --git a/application/controllers/Appointments.php b/application/controllers/Appointments.php
index 779d00bf..3df90e80 100755
--- a/application/controllers/Appointments.php
+++ b/application/controllers/Appointments.php
@@ -519,8 +519,8 @@ class Appointments extends CI_Controller {
         // Get the service, provider's working plan and provider appointments.
         $working_plan = json_decode($this->providers_model->get_setting('working_plan', $provider_id), TRUE);
 
-        // Get the provider's extra working plan.
-        $extra_working_plan = json_decode($this->providers_model->get_setting('extra_working_plan', $provider_id), TRUE);
+        // Get the provider's custom availability periods.
+        $custom_availability_periods = json_decode($this->providers_model->get_setting('custom_availability_periods', $provider_id), TRUE);
 
         $provider_appointments = $this->appointments_model->get_batch([
             'id_users_provider' => $provider_id,
@@ -543,12 +543,12 @@ class Appointments extends CI_Controller {
         // every reserved appointment is considered to be a taken space in the plan.
         $selected_date_working_plan = $working_plan[strtolower(date('l', strtotime($selected_date)))];
 
-        // Search if the $selected_date is an extra date added outside the normal working plan
+        // Search if the $selected_date is an custom availability period added outside the normal working plan.
         if ($selected_date_working_plan == NULL)
         {
-            if (isset($extra_working_plan[strtolower(date('Y-m-d', strtotime($selected_date)))]))
+            if (isset($custom_availability_periods[strtolower(date('Y-m-d', strtotime($selected_date)))]))
             {
-                $selected_date_working_plan = $extra_working_plan[strtolower(date('Y-m-d', strtotime($selected_date)))];
+                $selected_date_working_plan = $custom_availability_periods[strtolower(date('Y-m-d', strtotime($selected_date)))];
             }
         }
 
@@ -757,7 +757,7 @@ class Appointments extends CI_Controller {
     /**
      * Get multiple attendants hours.
      *
-     * This method will add the extra appointment hours whenever a service accepts multiple attendants.
+     * This method will add the additional appointment hours whenever a service accepts multiple attendants.
      *
      * @param string $selected_date The selected appointment date.
      * @param array $service Selected service data.
diff --git a/application/controllers/Backend.php b/application/controllers/Backend.php
index ed314b26..4948759c 100755
--- a/application/controllers/Backend.php
+++ b/application/controllers/Backend.php
@@ -333,7 +333,7 @@ class Backend extends CI_Controller {
         $view['services'] = $this->services_model->get_batch();
         $view['working_plan'] = $this->settings_model->get_setting('company_working_plan');
         $view['timezones'] = $this->timezones->to_array();
-        $view['extra_working_plan'] = '{}';
+        $view['custom_availability_periods'] = '{}';
         $this->set_user_data($view);
 
         $this->load->view('backend/header', $view);
diff --git a/application/controllers/Backend_api.php b/application/controllers/Backend_api.php
index 89f6e43d..e710f553 100755
--- a/application/controllers/Backend_api.php
+++ b/application/controllers/Backend_api.php
@@ -857,16 +857,16 @@ class Backend_api extends CI_Controller {
     }
 
     /**
-     * Insert of update extra working plan time period to database.
+     * Insert of update custom availability periods to database.
      */
-    public function ajax_save_extra_period()
+    public function ajax_save_custom_availability_period()
     {
         try
         {
             // Check privileges
-            $extra_period = json_decode($this->input->post('extra_period'), TRUE);
+            $custom_availability_period = json_decode($this->input->post('custom_availability_period'), TRUE);
 
-            $required_privileges = ( ! isset($extra_period['id']))
+            $required_privileges = ( ! isset($custom_availability_period['id']))
                 ? $this->privileges[PRIV_APPOINTMENTS]['add']
                 : $this->privileges[PRIV_APPOINTMENTS]['edit'];
             if ($required_privileges == FALSE)
@@ -876,7 +876,7 @@ class Backend_api extends CI_Controller {
 
             $this->load->model('providers_model');
 
-            $success = $this->providers_model->set_extra_working_day($extra_period, $extra_period['id_users_provider']);
+            $success = $this->providers_model->set_custom_availability_period($custom_availability_period, $custom_availability_period['id_users_provider']);
 
             if ($success)
             {
@@ -884,7 +884,7 @@ class Backend_api extends CI_Controller {
             }
             else
             {
-                $response = ['warnings' => 'Error on saving extra period.'];
+                $response = ['warnings' => 'Error on saving custom availability period.'];
             }
         }
         catch (Exception $exception)
@@ -903,9 +903,9 @@ class Backend_api extends CI_Controller {
     }
 
     /**
-     * Delete an extra working plan time period to database.
+     * Delete an custom availability periods time period to database.
      */
-    public function ajax_delete_extra_period()
+    public function ajax_delete_custom_availability_period()
     {
         try
         {
@@ -915,13 +915,13 @@ class Backend_api extends CI_Controller {
             }
 
             // Check privileges
-            $extra_period = $this->input->post('extra_period');
+            $custom_availability_period = $this->input->post('custom_availability_period');
             $provider_id = $this->input->post('provider_id');
 
             $this->load->model('providers_model');
 
             // Delete unavailable
-            $success = $this->providers_model->delete_extra_working_day($extra_period, $provider_id);
+            $success = $this->providers_model->delete_custom_availability_period($custom_availability_period, $provider_id);
 
             if ($success)
             {
@@ -929,7 +929,7 @@ class Backend_api extends CI_Controller {
             }
             else
             {
-                $response = ['warnings' => 'Error on deleting extra period.'];
+                $response = ['warnings' => 'Error on deleting custom availability period.'];
             }
         }
         catch (Exception $exception)
diff --git a/application/controllers/api/v1/Availabilities.php b/application/controllers/api/v1/Availabilities.php
index d05c2101..92714f76 100644
--- a/application/controllers/api/v1/Availabilities.php
+++ b/application/controllers/api/v1/Availabilities.php
@@ -369,13 +369,13 @@ class Availabilities extends API_V1_Controller {
     /**
      * Get multiple attendants hours.
      *
-     * This method will add the extra appointment hours whenever a service accepts multiple attendants.
+     * This method will add the additional appointment hours whenever a service accepts multiple attendants.
      *
      * @param string $selected_date The selected appointment date.
      * @param array $service Selected service data.
      * @param array $provider Selected provider data.
      *
-     * @return array Retunrs the available hours array.
+     * @return array Returns the available hours array.
      */
     protected function _getMultipleAttendantsHours(
         $selected_date,
diff --git a/application/language/arabic/translations_lang.php b/application/language/arabic/translations_lang.php
index f76f5c1f..e5368c81 100755
--- a/application/language/arabic/translations_lang.php
+++ b/application/language/arabic/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Delete all personal information fro
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/bulgarian/translations_lang.php b/application/language/bulgarian/translations_lang.php
index babbc889..513d8006 100755
--- a/application/language/bulgarian/translations_lang.php
+++ b/application/language/bulgarian/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Delete all personal information fro
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/catalan/translations_lang.php b/application/language/catalan/translations_lang.php
index 9aeb9a39..a8c95841 100644
--- a/application/language/catalan/translations_lang.php
+++ b/application/language/catalan/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Elimineu les vostres dades del sist
 $lang['delete_personal_information'] = 'Eliminació de dades personals';
 $lang['delete_personal_information_prompt'] = 'Esteu segur que voleu eliminar la vostra informació personal? Aquesta acció no es pot desfer.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/chinese/translations_lang.php b/application/language/chinese/translations_lang.php
index dff3de35..d6f71a5d 100755
--- a/application/language/chinese/translations_lang.php
+++ b/application/language/chinese/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Delete all personal information fro
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/czech/translations_lang.php b/application/language/czech/translations_lang.php
index 3911834d..73dc2536 100644
--- a/application/language/czech/translations_lang.php
+++ b/application/language/czech/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Odstranit ze systému všechny osob
 $lang['delete_personal_information'] = 'Odstranit osobní údaje';
 $lang['delete_personal_information_prompt'] = 'Jste si jisti, že chcete odstranit vaše osobní údaje? Tuto akci nelze vzít zpět.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/danish/translations_lang.php b/application/language/danish/translations_lang.php
index 2ebfc138..9c6743fe 100755
--- a/application/language/danish/translations_lang.php
+++ b/application/language/danish/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Slet alle dine personlige oplysning
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/dutch/translations_lang.php b/application/language/dutch/translations_lang.php
index ca68e66f..cb7e6058 100755
--- a/application/language/dutch/translations_lang.php
+++ b/application/language/dutch/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Delete all personal information fro
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/english/translations_lang.php b/application/language/english/translations_lang.php
index 53379cdb..845cf844 100755
--- a/application/language/english/translations_lang.php
+++ b/application/language/english/translations_lang.php
@@ -300,13 +300,13 @@ $lang['delete_personal_information_hint'] = 'Remove all your appointments and pe
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/finnish/translations_lang.php b/application/language/finnish/translations_lang.php
index 654d2b30..0891574b 100755
--- a/application/language/finnish/translations_lang.php
+++ b/application/language/finnish/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Delete all personal information fro
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/french/translations_lang.php b/application/language/french/translations_lang.php
index 3ed8c950..76ef6a02 100755
--- a/application/language/french/translations_lang.php
+++ b/application/language/french/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Effacer toutes vos données personn
 $lang['delete_personal_information'] = 'Effacer toutes mes données personnelles';
 $lang['delete_personal_information_prompt'] = 'Etes-vous sûr(e) de vouloir effacer toutes vos données personnelles ? Cette action est irréversible.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/german/translations_lang.php b/application/language/german/translations_lang.php
index 3064e007..2a083d48 100755
--- a/application/language/german/translations_lang.php
+++ b/application/language/german/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Entfernen Sie alle Ihre Termine und
 $lang['delete_personal_information'] = 'Persönlichen Informationen löschen';
 $lang['delete_personal_information_prompt'] = 'Sind Sie sicher, dass Sie Ihre persönlichen Daten löschen möchten? Diese Aktion kann nicht rückgängig gemacht werden.';
 $lang['location'] = 'Ort';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/greek/translations_lang.php b/application/language/greek/translations_lang.php
index 50068166..2e9eac4f 100755
--- a/application/language/greek/translations_lang.php
+++ b/application/language/greek/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Κατάργηση όλων των
 $lang['delete_personal_information'] = 'Διαγραφή Προσωπικών Πληροφοριών';
 $lang['delete_personal_information_prompt'] = 'Είστε σίγουρος ότι θέλετε να διαγράψετε τις προσωπικές σας πληροφορίες; Αυτή η ενέργεια δεν μπορεί να αναιρεθεί.';
 $lang['location'] = 'Τοποθεσία';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/hindi/translations_lang.php b/application/language/hindi/translations_lang.php
index 38281034..6b0dc6b1 100755
--- a/application/language/hindi/translations_lang.php
+++ b/application/language/hindi/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Delete all personal information fro
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/hungarian/translations_lang.php b/application/language/hungarian/translations_lang.php
index a9824b37..77a8f6c7 100755
--- a/application/language/hungarian/translations_lang.php
+++ b/application/language/hungarian/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Delete all personal information fro
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/italian/translations_lang.php b/application/language/italian/translations_lang.php
index 21101f99..521bc27b 100755
--- a/application/language/italian/translations_lang.php
+++ b/application/language/italian/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Cancella tutti i dati personali dal
 $lang['delete_personal_information'] = 'Cancella dati personali';
 $lang['delete_personal_information_prompt'] = 'Sicuro di voler cancellare i tuoi dati personali? Questa operazione è irreversibile.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Giorno extra';
-$lang['extra_periods'] = 'Giorni Extra';
-$lang['extra_periods_hint'] = 'Aggiungi una giornata lavorativa al di fuori del piano di lavoro.';
-$lang['new_extra_period_title'] = 'Nuova giornata lavorativa';
-$lang['extra_period_saved'] = 'Giornata lavorativa salvata con successo!';
-$lang['add_extra_periods_during_each_day'] = 'Aggiungi giornate lavorative al di fuori del piano di lavoro.';
-$lang['add_extra_period'] = 'Aggiungi giornata lavorativa';
+$lang['custom_availability_period'] = 'Giorno extra';
+$lang['custom_availability_periods'] = 'Giorni Extra';
+$lang['custom_availability_periods_hint'] = 'Aggiungi una giornata lavorativa al di fuori del piano di lavoro.';
+$lang['new_custom_availability_period_title'] = 'Nuova giornata lavorativa';
+$lang['custom_availability_period_saved'] = 'Giornata lavorativa salvata con successo!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Aggiungi giornate lavorative al di fuori del piano di lavoro.';
+$lang['add_custom_availability_period'] = 'Aggiungi giornata lavorativa';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/japanese/translations_lang.php b/application/language/japanese/translations_lang.php
index b51e512f..6ea00436 100755
--- a/application/language/japanese/translations_lang.php
+++ b/application/language/japanese/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Delete all personal information fro
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/luxembourgish/translations_lang.php b/application/language/luxembourgish/translations_lang.php
index 5b2b9651..15546526 100755
--- a/application/language/luxembourgish/translations_lang.php
+++ b/application/language/luxembourgish/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Delete all personal information fro
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/marathi/translations_lang.php b/application/language/marathi/translations_lang.php
index 3057516c..c38a4e6a 100644
--- a/application/language/marathi/translations_lang.php
+++ b/application/language/marathi/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'सिस्टमवरून स
 $lang['delete_personal_information'] = 'वैयक्तिक माहिती हटवा';
 $lang['delete_personal_information_prompt'] = 'आपली खात्री आहे की आपण आपली वैयक्तिक माहिती हटवू इच्छिता? ही क्रिया पूर्ववत करणे शक्य नाही.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/polish/translations_lang.php b/application/language/polish/translations_lang.php
index ca41c520..cb8531ca 100755
--- a/application/language/polish/translations_lang.php
+++ b/application/language/polish/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Delete all personal information fro
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/portuguese-br/translations_lang.php b/application/language/portuguese-br/translations_lang.php
index cd2687f7..5a8ebcec 100755
--- a/application/language/portuguese-br/translations_lang.php
+++ b/application/language/portuguese-br/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Deletar toda informação pessoal d
 $lang['delete_personal_information'] = 'Deletar Informação Pessoal';
 $lang['delete_personal_information_prompt'] = 'Tem certeza que deja deletar suas informações pessoais? Essa ação não pode ser desfeita.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/portuguese/translations_lang.php b/application/language/portuguese/translations_lang.php
index bd51b198..5b48ac64 100755
--- a/application/language/portuguese/translations_lang.php
+++ b/application/language/portuguese/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Delete all personal information fro
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/romanian/translations_lang.php b/application/language/romanian/translations_lang.php
index e00ee293..992d49d0 100755
--- a/application/language/romanian/translations_lang.php
+++ b/application/language/romanian/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Delete all personal information fro
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/russian/translations_lang.php b/application/language/russian/translations_lang.php
index 1886a8c1..7877df3f 100755
--- a/application/language/russian/translations_lang.php
+++ b/application/language/russian/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Delete all personal information fro
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/slovak/translations_lang.php b/application/language/slovak/translations_lang.php
index 04ec9f79..babc0ee0 100755
--- a/application/language/slovak/translations_lang.php
+++ b/application/language/slovak/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Delete all personal information fro
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/spanish/translations_lang.php b/application/language/spanish/translations_lang.php
index fe6388ca..89ebfc5d 100755
--- a/application/language/spanish/translations_lang.php
+++ b/application/language/spanish/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Borrar toda la información persona
 $lang['delete_personal_information'] = 'Borrar información personal';
 $lang['delete_personal_information_prompt'] = '¿Estás seguro que quieres borrar tu información personal? Esta acción no se puede deshacer.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/language/swedish/translations_lang.php b/application/language/swedish/translations_lang.php
index 18c0090a..b2bdccf4 100755
--- a/application/language/swedish/translations_lang.php
+++ b/application/language/swedish/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Ta bort all dina personliga uppgift
 $lang['delete_personal_information'] = 'Ta bort Personlig Information';
 $lang['delete_personal_information_prompt'] = 'Är du säker på att du vill ta bort all information om dig från systemet? Det går inte att återställa informationen om du ångrar dig.';
 $lang['location'] = 'Plats';
-$lang['extra_period'] = 'Extra arbetsdag';
-$lang['extra_periods'] = 'Extra arbetsdagar';
-$lang['extra_periods_hint'] = 'Lägg till en arbetsdag utanför schemat.';
-$lang['new_extra_period_title'] = 'Ny arbetsdag';
-$lang['extra_period_saved'] = 'Den nya arbetsdagen är sparad.';
-$lang['add_extra_periods_during_each_day'] = 'Lägg till arbetsdagar utanför schemat.';
-$lang['add_extra_period'] = 'Lägg till en arbetsdag.';
+$lang['custom_availability_period'] = 'Extra arbetsdag';
+$lang['custom_availability_periods'] = 'Extra arbetsdagar';
+$lang['custom_availability_periods_hint'] = 'Lägg till en arbetsdag utanför schemat.';
+$lang['new_custom_availability_period_title'] = 'Ny arbetsdag';
+$lang['custom_availability_period_saved'] = 'Den nya arbetsdagen är sparad.';
+$lang['add_custom_availability_periods_during_each_day'] = 'Lägg till arbetsdagar utanför schemat.';
+$lang['add_custom_availability_period'] = 'Lägg till en arbetsdag.';
 $lang['require_phone_number'] = 'Kräv telefonnummer.';
 $lang['require_phone_number_hint'] = 'När denna är aktiv måste kunderna ange ett telefonnummer för att kunna göra en bokning.';
 $lang['check_spam_folder'] = 'Om eposten inte kommit fram inom några minuter; kolla skräpposten.';
diff --git a/application/language/turkish/translations_lang.php b/application/language/turkish/translations_lang.php
index 6c306bf5..e1d24a6f 100755
--- a/application/language/turkish/translations_lang.php
+++ b/application/language/turkish/translations_lang.php
@@ -298,13 +298,13 @@ $lang['delete_personal_information_hint'] = 'Delete all personal information fro
 $lang['delete_personal_information'] = 'Delete Personal Information';
 $lang['delete_personal_information_prompt'] = 'Are you sure that you want to delete your personal information? This action cannot be undone.';
 $lang['location'] = 'Location';
-$lang['extra_period'] = 'Extra working day';
-$lang['extra_periods'] = 'Extra working days';
-$lang['extra_periods_hint'] = 'Add a working day outside the working plan.';
-$lang['new_extra_period_title'] = 'New working day';
-$lang['extra_period_saved'] = 'New working day saved successfully!';
-$lang['add_extra_periods_during_each_day'] = 'Add working days outside the working plan.';
-$lang['add_extra_period'] = 'Add a working day';
+$lang['custom_availability_period'] = 'Custom availability period';
+$lang['custom_availability_periods'] = 'Custom availability periods';
+$lang['custom_availability_periods_hint'] = 'Add a working day outside the working plan.';
+$lang['new_custom_availability_period_title'] = 'New working day';
+$lang['custom_availability_period_saved'] = 'New working day saved successfully!';
+$lang['add_custom_availability_periods_during_each_day'] = 'Add working days outside the working plan.';
+$lang['add_custom_availability_period'] = 'Add a working day';
 $lang['require_phone_number'] = 'Require phone number';
 $lang['require_phone_number_hint'] = 'When enabled, customers and users will need to enter the customer\'s phone number when booking an appointment';
 $lang['check_spam_folder'] = 'Please check your spam folder if the email does not arrive within a few minutes.';
diff --git a/application/migrations/015_add_extra_working_plan_to_user_settings.php b/application/migrations/015_add_extra_working_plan_to_user_settings.php
index 90522bd7..7ae20c96 100644
--- a/application/migrations/015_add_extra_working_plan_to_user_settings.php
+++ b/application/migrations/015_add_extra_working_plan_to_user_settings.php
@@ -12,21 +12,21 @@
  * ---------------------------------------------------------------------------- */
 
 /**
- * Class Migration_Add_extra_working_plan_to_user_settings
+ * Class Migration_Add_custom_availability_periods_to_user_settings
  *
  * @property CI_DB_query_builder db
  * @property CI_DB_forge dbforge
  */
-class Migration_Add_extra_working_plan_to_user_settings extends CI_Migration {
+class Migration_Add_custom_availability_periods_to_user_settings extends CI_Migration {
     /**
      * Upgrade method.
      */
     public function up()
     {
-        if ( ! $this->db->field_exists('extra_working_plan', 'user_settings'))
+        if ( ! $this->db->field_exists('custom_availability_periods', 'user_settings'))
         {
             $fields = [
-                'extra_working_plan' => [
+                'custom_availability_periods' => [
                     'type' => 'TEXT',
                     'null' => TRUE,
                     'after' => 'working_plan'
@@ -42,9 +42,9 @@ class Migration_Add_extra_working_plan_to_user_settings extends CI_Migration {
      */
     public function down()
     {
-        if ( ! $this->db->field_exists('extra_working_plan', 'user_settings'))
+        if ( ! $this->db->field_exists('custom_availability_periods', 'user_settings'))
         {
-            $this->dbforge->drop_column('user_settings', 'extra_working_plan');
+            $this->dbforge->drop_column('user_settings', 'custom_availability_periods');
         }
     }
 }
diff --git a/application/models/Providers_model.php b/application/models/Providers_model.php
index 394da1a8..141bba4f 100755
--- a/application/models/Providers_model.php
+++ b/application/models/Providers_model.php
@@ -322,8 +322,8 @@ class Providers_Model extends CI_Model {
 
         foreach ($settings as $name => $value)
         {
-            // Sort in descending order the extra working plan days
-            if ($name == 'extra_working_plan')
+            // Sort in descending order the custom availability periods
+            if ($name == 'custom_availability_periods')
             {
                 $value = json_decode($value, TRUE);
                 // Sort the array and put in reverse order
@@ -634,22 +634,22 @@ class Providers_Model extends CI_Model {
     }
 
     /**
-     * Save the provider extra working plan days.
+     * Save the provider custom availability period.
      *
-     * @param array $extra_period Contains the date and the hours of the extra working plan day.
+     * @param array $custom_availability_period Contains the date and the hours of the Custom availability period.
      * @param int $provider_id The selected provider record id.
      *
-     * @return bool Return if the new extra working plan is correctly saved to DB.
+     * @return bool Return if the new custom availability periods is correctly saved to DB.
      *
      * @throws Exception If start time is after the end time.
      * @throws Exception If $provider_id argument is invalid.
      */
-    public function set_extra_working_day($extra_period, $provider_id)
+    public function set_custom_availability_period($custom_availability_period, $provider_id)
     {
         // Validate period
-        $dateStart = date('Y-m-d', strtotime($extra_period['start_datetime']));
-        $start = date('H:i', strtotime($extra_period['start_datetime']));
-        $end = date('H:i', strtotime($extra_period['end_datetime']));
+        $dateStart = date('Y-m-d', strtotime($custom_availability_period['start_datetime']));
+        $start = date('H:i', strtotime($custom_availability_period['start_datetime']));
+        $end = date('H:i', strtotime($custom_availability_period['end_datetime']));
         if ($start > $end)
         {
             throw new Exception('Unavailable period start must be prior to end.');
@@ -667,17 +667,15 @@ class Providers_Model extends CI_Model {
         }
 
         // Add record to database.
-        $extra_working_plan = json_decode($this->get_setting('extra_working_plan', $provider_id), TRUE);
+        $custom_availability_periods = json_decode($this->get_setting('custom_availability_periods', $provider_id), TRUE);
 
-        $extra_working_plan[$dateStart] = [
+        $custom_availability_periods[$dateStart] = [
             'start' => $start,
             'end' => $end,
             'breaks' => []
         ];
 
-        $success = $this->set_setting('extra_working_plan', json_encode($extra_working_plan), $provider_id);
-
-        return $success;
+        return $this->set_setting('custom_availability_periods', json_encode($custom_availability_periods), $provider_id);
     }
 
     /**
@@ -695,16 +693,16 @@ class Providers_Model extends CI_Model {
     }
 
     /**
-     * Delete a provider extra working plan day.
+     * Delete a provider custom availability period.
      *
-     * @param string $extra_period Contains the date to be deleted from the extra working plan.
+     * @param string $custom_availability_period Contains the date to be deleted from the custom availability periods.
      * @param int $provider_id The selected provider record id.
      *
-     * @return bool Return if the new extra working plan is correctly deleted from DB.
+     * @return bool Return if the new custom availability periods is correctly deleted from DB.
      *
      * @throws Exception If $provider_id argument is invalid.
      */
-    public function delete_extra_working_day($extra_period, $provider_id)
+    public function delete_custom_availability_period($custom_availability_period, $provider_id)
     {
         // Validate provider record
         $where_clause = [
@@ -718,12 +716,10 @@ class Providers_Model extends CI_Model {
         }
 
         // Add record to database.
-        $extra_working_plan = json_decode($this->get_setting('extra_working_plan', $provider_id), TRUE);
+        $custom_availability_periods = json_decode($this->get_setting('custom_availability_periods', $provider_id), TRUE);
 
-        unset($extra_working_plan[$extra_period]);
+        unset($custom_availability_periods[$custom_availability_period]);
 
-        $success = $this->set_setting('extra_working_plan', json_encode($extra_working_plan), $provider_id);
-
-        return $success;
+        return $this->set_setting('custom_availability_periods', json_encode($custom_availability_periods), $provider_id);
     }
 }
diff --git a/application/views/backend/calendar.php b/application/views/backend/calendar.php
index 7c27ba7c..32f7ec68 100755
--- a/application/views/backend/calendar.php
+++ b/application/views/backend/calendar.php
@@ -9,7 +9,7 @@
 <script src="<?= asset_url('assets/js/backend_calendar_google_sync.js') ?>"></script>
 <script src="<?= asset_url('assets/js/backend_calendar_appointments_modal.js') ?>"></script>
 <script src="<?= asset_url('assets/js/backend_calendar_unavailabilities_modal.js') ?>"></script>
-<script src="<?= asset_url('assets/js/backend_calendar_extra_periods_modal.js') ?>"></script>
+<script src="<?= asset_url('assets/js/backend_calendar_custom_availability_periods_modal.js') ?>"></script>
 <script src="<?= asset_url('assets/js/backend_calendar_api.js') ?>"></script>
 <script>
     var GlobalVariables = {
@@ -83,9 +83,9 @@
                         <i class="far fa-plus-square mr-2"></i>
                         <?= lang('unavailable') ?>
                     </a>
-                    <a class="dropdown-item" href="#" id="insert-extra-period">
+                    <a class="dropdown-item" href="#" id="insert-custom-availability-period">
                         <i class="far fa-plus-square mr-2"></i>
-                        <?= lang('extra_period') ?>
+                        <?= lang('custom_availability_period') ?>
                     </a>
                 </div>
             </div>
@@ -117,7 +117,7 @@
 
 <!-- MANAGE APPOINTMENT MODAL -->
 
-<div id="manage-appointment" class="modal fade" data-keyboard="true" tabindex="-1">
+<div id="manage-appointment" class="modal fade" tabindex="-1">
     <div class="modal-dialog modal-lg">
         <div class="modal-content">
             <div class="modal-header">
@@ -355,7 +355,7 @@
 
 <!-- MANAGE UNAVAILABLE MODAL -->
 
-<div id="manage-unavailable" class="modal fade">
+<div id="manage-unavailable" class="modal fade" tabindex="-1">
     <div class="modal-dialog">
         <div class="modal-content">
             <div class="modal-header">
@@ -424,13 +424,13 @@
     </div>
 </div>
 
-<!-- MANAGE EXTRA PERIOD MODAL -->
+<!-- MANAGE CUSTOM AVAILABILITY PERIODS MODAL -->
 
-<div id="manage-extra" class="modal fade">
+<div id="manage-custom-availability-periods" class="modal fade" tabindex="-1">
     <div class="modal-dialog">
         <div class="modal-content">
             <div class="modal-header">
-                <h3 class="modal-title"><?= lang('new_extra_period_title') ?></h3>
+                <h3 class="modal-title"><?= lang('new_custom_availability_period_title') ?></h3>
                 <button class="close" data-dismiss="modal">&times;</button>
             </div>
             <div class="modal-body">
@@ -438,21 +438,21 @@
 
                 <form>
                     <fieldset>
-                        <input id="extra-id" type="hidden">
+                        <input id="custom-availability-period-id" type="hidden">
 
                         <div class="form-group">
-                            <label for="extra-provider" class="control-label"><?= lang('provider') ?></label>
-                            <select id="extra-provider" class="form-control"></select>
+                            <label for="custom-availability-period-provider" class="control-label"><?= lang('provider') ?></label>
+                            <select id="custom-availability-period-provider" class="form-control"></select>
                         </div>
 
                         <div class="form-group">
-                            <label for="extra-start" class="control-label"><?= lang('start') ?></label>
-                            <input id="extra-start" class="form-control">
+                            <label for="custom-availability-period-start" class="control-label"><?= lang('start') ?></label>
+                            <input id="custom-availability-period-start" class="form-control">
                         </div>
 
                         <div class="form-group">
-                            <label for="extra-end" class="control-label"><?= lang('end') ?></label>
-                            <input id="extra-end" class="form-control">
+                            <label for="custom-availability-period-end" class="control-label"><?= lang('end') ?></label>
+                            <input id="custom-availability-period-end" class="form-control">
                         </div>
 
                         <div class="form-group">
@@ -477,11 +477,11 @@
                 </form>
             </div>
             <div class="modal-footer">
-                <button id="cancel-extra" class="btn btn-light" data-dismiss="modal">
+                <button id="cancel-custom-availability-period" class="btn btn-light" data-dismiss="modal">
                     <i class="fas fa-ban"></i>
                     <?= lang('cancel') ?>
                 </button>
-                <button id="save-extra" class="btn btn-primary">
+                <button id="save-custom-availability-period" class="btn btn-primary">
                     <i class="far fa-check-square mr-2"></i>
                     <?= lang('save') ?>
                 </button>
diff --git a/application/views/backend/users.php b/application/views/backend/users.php
index 20d3c47f..be904d0f 100755
--- a/application/views/backend/users.php
+++ b/application/views/backend/users.php
@@ -18,7 +18,7 @@
         services: <?= json_encode($services) ?>,
         timezones: <?= json_encode($timezones) ?>,
         workingPlan: <?= json_encode(json_decode($working_plan)) ?>,
-        extraWorkingPlan: <?= json_encode(json_decode($extra_working_plan)) ?>,
+        customavailabilityperiods: <?= json_encode(json_decode($custom_availability_periods)) ?>,
         user: {
             id: <?= $user_id ?>,
             email: <?= json_encode($user_email) ?>,
@@ -290,22 +290,22 @@
 
                             <br>
 
-                            <h3><?= lang('extra_periods') ?></h3>
+                            <h3><?= lang('custom_availability_periods') ?></h3>
 
                             <span class="help-block">
-                            <?= lang('add_extra_periods_during_each_day') ?>
+                            <?= lang('add_custom_availability_periods_during_each_day') ?>
                         </span>
 
                             <div>
-                                <button type="button" class="add-extra-periods btn btn-primary mr-2">
+                                <button type="button" class="add-custom-availability-periods btn btn-primary mr-2">
                                     <i class="far fa-plus-square"></i>
-                                    <?= lang('add_extra_period') ?>
+                                    <?= lang('add_custom_availability_period') ?>
                                 </button>
                             </div>
 
                             <br>
 
-                            <table class="extra-periods table table-striped">
+                            <table class="custom-availability-periods table table-striped">
                                 <thead>
                                 <tr>
                                     <th><?= lang('day') ?></th>
diff --git a/assets/css/backend.css b/assets/css/backend.css
index b5a5df3e..dac4bcdd 100644
--- a/assets/css/backend.css
+++ b/assets/css/backend.css
@@ -148,8 +148,7 @@ body .modal .modal-title {
 
 body .modal-header {
     padding: 12px 15px;
-    background: #39c678;
-    border-bottom: 4px solid #c0f1d6;
+    background: #429a82;
 }
 
 body .modal-header h3 {
@@ -726,7 +725,7 @@ body .form-horizontal .controls {
     padding: 4px 7px;
 }
 
-#users-page #providers .extra-periods .btn {
+#users-page #providers .custom-availability-periods .btn {
     margin-right: 5px;
     padding: 4px 7px;
 }
@@ -736,7 +735,7 @@ body .form-horizontal .controls {
         height: 36px;
     }
 
-    .extra-periods .extra-day select {
+    .custom-availability-periods .custom-availability-period select {
         height: 36px;
     }
 }
diff --git a/assets/js/backend_calendar.js b/assets/js/backend_calendar.js
index 1f30959b..fd393f10 100755
--- a/assets/js/backend_calendar.js
+++ b/assets/js/backend_calendar.js
@@ -78,7 +78,7 @@ window.BackendCalendar = window.BackendCalendar || {};
         BackendCalendarGoogleSync.initialize();
         BackendCalendarAppointmentsModal.initialize();
         BackendCalendarUnavailabilitiesModal.initialize();
-        BackendCalendarExtraPeriodsModal.initialize();
+        BackendCalendarCustomAvailabilityPeriodsModal.initialize();
 
         // Load and initialize the calendar view.
         if (view === 'table') {
diff --git a/assets/js/backend_calendar_api.js b/assets/js/backend_calendar_api.js
index b5601c61..133a2dd3 100755
--- a/assets/js/backend_calendar_api.js
+++ b/assets/js/backend_calendar_api.js
@@ -91,18 +91,18 @@ window.BackendCalendarApi = window.BackendCalendarApi || {};
     };
 
     /**
-     * Save extra period of work to database.
+     * Save custom availability period of work to database.
      *
-     * @param {Object} extra_periods Contains the extra period data.
+     * @param {Object} customAvailabilityPeriods Contains the custom availability periods data.
      * @param {Function} successCallback The ajax success callback function.
      * @param {Function} errorCallback The ajax failure callback function.
      */
-    exports.saveExtraPeriod = function (extra_periods, successCallback, errorCallback) {
-        var url = GlobalVariables.baseUrl + '/index.php/backend_api/ajax_save_extra_period';
+    exports.saveCustomavailabilityperiod = function (customAvailabilityPeriods, successCallback, errorCallback) {
+        var url = GlobalVariables.baseUrl + '/index.php/backend_api/ajax_save_custom_availability_period';
 
         var data = {
             csrfToken: GlobalVariables.csrfToken,
-            extra_period: JSON.stringify(extra_periods)
+            custom_availability_period: JSON.stringify(customAvailabilityPeriods)
         };
 
         $.post(url, data)
diff --git a/assets/js/backend_calendar_extra_periods_modal.js b/assets/js/backend_calendar_custom_availability_periods_modal.js
similarity index 56%
rename from assets/js/backend_calendar_extra_periods_modal.js
rename to assets/js/backend_calendar_custom_availability_periods_modal.js
index 62bcebc1..ba928088 100644
--- a/assets/js/backend_calendar_extra_periods_modal.js
+++ b/assets/js/backend_calendar_custom_availability_periods_modal.js
@@ -10,13 +10,13 @@
  * ---------------------------------------------------------------------------- */
 
 /**
- * Backend Calendar Extra Periods Modal
+ * Backend Calendar Custom availability periods Modal
  *
- * This module implements the extra periods modal functionality.
+ * This module implements the custom availability periods modal functionality.
  *
- * @module BackendCalendarExtraPeriodsModal
+ * @module BackendCalendarCustomAvailabilityPeriodsModal
  */
-window.BackendCalendarExtraPeriodsModal = window.BackendCalendarExtraPeriodsModal || {};
+window.BackendCalendarCustomAvailabilityPeriodsModal = window.BackendCalendarCustomAvailabilityPeriodsModal || {};
 
 (function (exports) {
 
@@ -24,15 +24,15 @@ window.BackendCalendarExtraPeriodsModal = window.BackendCalendarExtraPeriodsModa
 
     function bindEventHandlers() {
         /**
-         * Event: Manage extra Dialog Save Button "Click"
+         * Event: Manage Dialog Save Button "Click"
          *
-         * Stores the extra period changes or inserts a new record.
+         * Stores the custom availability period changes or inserts a new record.
          */
-        $('#manage-extra #save-extra').on('click', function () {
-            var $dialog = $('#manage-extra');
+        $('#manage-custom-availability-periods #save-custom-availability-period').on('click', function () {
+            var $dialog = $('#manage-custom-availability-periods');
             $dialog.find('.has-error').removeClass('has-error');
-            var start = $dialog.find('#extra-start').datetimepicker('getDate');
-            var end = Date.parse($dialog.find('#extra-end').datetimepicker('getDate'));
+            var start = $dialog.find('#custom-availability-period-start').datetimepicker('getDate');
+            var end = Date.parse($dialog.find('#custom-availability-period-end').datetimepicker('getDate'));
 
             if (start.toString('HH:mm') > end.toString('HH:mm')) {
                 // Start time is after end time - display message to user.
@@ -41,43 +41,43 @@ window.BackendCalendarExtraPeriodsModal = window.BackendCalendarExtraPeriodsModa
                     .addClass('alert-danger')
                     .removeClass('hidden');
 
-                $dialog.find('#extra-start, #extra-end').closest('.form-group').addClass('has-error');
+                $dialog.find('#custom-availability-period-start, #custom-availability-period-end').closest('.form-group').addClass('has-error');
                 return;
             }
 
-            // extra period records go to the appointments table.
-            var extra = {
+            // Custom availability period period records go to the appointments table.
+            var customAvailabilityPeriod = {
                 start_datetime: start.toString('yyyy-MM-dd HH:mm'),
                 end_datetime: start.toString('yyyy-MM-dd') + ' ' + end.toString('HH:mm'),
-                id_users_provider: $('#extra-provider').val() // curr provider
+                id_users_provider: $('#custom-availability-period-provider').val() // curr provider
             };
 
-            //if ($dialog.find('#extra-id').val() !== '') {
-            //    // Set the id value, only if we are editing an appointment.
-            //    extra.id = $dialog.find('#extra-id').val();
+            //if ($dialog.find('#custom-availability-period-id').val() !== '') {
+            //    // Set the id value, only if we are editing a custom availability period.
+            //    customAvailabilityPeriod.id = $dialog.find('#custom-availability-period-id').val();
             //}
 
             var successCallback = function (response) {
                 // Display success message to the user.
-                Backend.displayNotification(EALang.extra_period_saved);
+                Backend.displayNotification(EALang.custom_availability_period_saved);
 
                 // Close the modal dialog and refresh the calendar appointments.
                 $dialog.find('.alert').addClass('hidden');
                 $dialog.modal('hide');
 
-                var providerId = $('#extra-provider').val();
+                var providerId = $('#custom-availability-period-provider').val();
                 var provider = GlobalVariables.availableProviders.filter(function (p) {
                     return p.id === providerId;
                 })[0];
                 var providerIdx = GlobalVariables.availableProviders.indexOf(provider);
 
-                var extraWorkingPlan = jQuery.parseJSON(provider.settings.extra_working_plan);
-                extraWorkingPlan[start.toString('yyyy-MM-dd')] = {
+                var customAvailabilityPeriods = jQuery.parseJSON(provider.settings.custom_availability_periods);
+                customAvailabilityPeriods[start.toString('yyyy-MM-dd')] = {
                     start: start.toString('HH:mm'),
                     end: end.toString('HH:mm'),
                     breaks: []
                 };
-                provider.settings.extra_working_plan = JSON.stringify(extraWorkingPlan);
+                provider.settings.custom_availability_periods = JSON.stringify(customAvailabilityPeriods);
                 GlobalVariables.availableProviders[providerIdx] = provider;
 
                 $('#select-filter-item').trigger('change');
@@ -88,27 +88,27 @@ window.BackendCalendarExtraPeriodsModal = window.BackendCalendarExtraPeriodsModa
                 $dialog.find('.modal-message').addClass('alert-danger').removeClass('hidden');
             };
 
-            BackendCalendarApi.saveExtraPeriod(extra, successCallback, errorCallback);
+            BackendCalendarApi.saveCustomavailabilityperiod(customAvailabilityPeriod, successCallback, errorCallback);
         });
 
         /**
-         * Event: Manage extra Dialog Cancel Button "Click"
+         * Event: Manage Dialog Cancel Button "Click"
          *
-         * Closes the dialog without saveing any changes to the database.
+         * Closes the dialog without saving any changes to the database.
          */
-        $('#manage-extra #cancel-extra').on('click', function () {
-            $('#manage-extra').modal('hide');
+        $('#manage-custom-availability-periods #cancel-custom-availability-period').on('click', function () {
+            $('#manage-custom-availability-periods').modal('hide');
         });
 
         /**
-         * Event : Insert extra Time Period Button "Click"
+         * Event: Insert Custom Working Time Period Button "Click"
          *
-         * When the user clicks this button a popup dialog appears and the use can set a time period where
-         * he cannot accept any appointments.
+         * When the user clicks this button a popup dialog appears and the use can set a time period where he cannot
+         * accept any appointments.
          */
-        $('#insert-extra-period').on('click', function () {
-            BackendCalendarExtraPeriodsModal.resetExtraDialog();
-            var $dialog = $('#manage-extra');
+        $('#insert-custom-availability-period').on('click', function () {
+            BackendCalendarCustomAvailabilityPeriodsModal.resetCustomavailabilityperiodDialog();
+            var $dialog = $('#manage-custom-availability-periods');
 
             // Set the default datetime values.
             var start = new Date();
@@ -117,29 +117,29 @@ window.BackendCalendarExtraPeriodsModal = window.BackendCalendarExtraPeriodsModa
             start.set({'minute': 30});
 
             if ($('.calendar-view').length === 0) {
-                $dialog.find('#extra-provider')
+                $dialog.find('#custom-availability-period-provider')
                     .val($('#select-filter-item').val())
                     .closest('.form-group')
                     .hide();
             }
 
-            $dialog.find('#extra-start').val(GeneralFunctions.formatDate(start, GlobalVariables.dateFormat, true));
-            $dialog.find('#extra-end').val(GlobalVariables.timeFormat === 'regular' ? '8:00 PM' : '19:00');
-            $dialog.find('.modal-header h3').text(EALang.new_extra_period_title);
+            $dialog.find('#custom-availability-period-start').val(GeneralFunctions.formatDate(start, GlobalVariables.dateFormat, true));
+            $dialog.find('#custom-availability-period-end').val(GlobalVariables.timeFormat === 'regular' ? '8:00 PM' : '19:00');
+            $dialog.find('.modal-header h3').text(EALang.new_custom_availability_period_title);
             $dialog.modal('show');
         });
     }
 
     /**
-     * Reset extra dialog form.
+     * Reset custom availability period dialog form.
      *
-     * Reset the "#manage-extra" dialog. Use this method to bring the dialog to the initial state
+     * Reset the "#manage-custom-availability-periods" dialog. Use this method to bring the dialog to the initial state
      * before it becomes visible to the user.
      */
-    exports.resetExtraDialog = function () {
-        var $dialog = $('#manage-extra');
+    exports.resetCustomavailabilityperiodDialog = function () {
+        var $dialog = $('#manage-custom-availability-periods');
 
-        $dialog.find('#extra-id').val('');
+        $dialog.find('#custom-availability-period-id').val('');
 
         // Set the default datetime values.
         var start = new Date();
@@ -163,7 +163,7 @@ window.BackendCalendarExtraPeriodsModal = window.BackendCalendarExtraPeriodsModa
         }
 
 
-        $dialog.find('#extra-start').datetimepicker({
+        $dialog.find('#custom-availability-period-start').datetimepicker({
             dateFormat: dateFormat,
             timeFormat: GlobalVariables.timeFormat === 'regular' ? 'h:mm tt' : GlobalVariables.timeFormat,
 
@@ -191,10 +191,10 @@ window.BackendCalendarExtraPeriodsModal = window.BackendCalendarExtraPeriodsModa
             minuteText: EALang.minutes,
             firstDay: 0
         });
-        $dialog.find('#extra-start').val(GeneralFunctions.formatDate(start, GlobalVariables.dateFormat, true));
-        $dialog.find('#extra-start').draggable();
+        $dialog.find('#custom-availability-period-start').val(GeneralFunctions.formatDate(start, GlobalVariables.dateFormat, true));
+        $dialog.find('#custom-availability-period-start').draggable();
 
-        $dialog.find('#extra-end').timepicker({
+        $dialog.find('#custom-availability-period-end').timepicker({
             timeFormat: GlobalVariables.timeFormat === 'regular' ? 'h:mm tt' : GlobalVariables.timeFormat,
             currentText: EALang.now,
             closeText: EALang.close,
@@ -203,22 +203,22 @@ window.BackendCalendarExtraPeriodsModal = window.BackendCalendarExtraPeriodsModa
             hourText: EALang.hour,
             minuteText: EALang.minutes
         });
-        $dialog.find('#extra-end').val(end);
+        $dialog.find('#custom-availability-period-end').val(end);
 
-        // Clear the extra notes field.
-        $dialog.find('#extra-notes').val('');
+        // Clear the custom availability period notes field.
+        $dialog.find('#custom-availability-period-notes').val('');
     };
 
     exports.initialize = function () {
-        var extraProvider = $('#extra-provider');
+        var customAvailabilityPeriodProvider = $('#custom-availability-period-provider');
 
         for (var index in GlobalVariables.availableProviders) {
             var provider = GlobalVariables.availableProviders[index];
 
-            extraProvider.append(new Option(provider.first_name + ' ' + provider.last_name, provider.id));
+            customAvailabilityPeriodProvider.append(new Option(provider.first_name + ' ' + provider.last_name, provider.id));
         }
 
         bindEventHandlers();
     };
 
-})(window.BackendCalendarExtraPeriodsModal);
+})(window.BackendCalendarCustomAvailabilityPeriodsModal);
diff --git a/assets/js/backend_calendar_default_view.js b/assets/js/backend_calendar_default_view.js
index 578d2724..26d753ac 100755
--- a/assets/js/backend_calendar_default_view.js
+++ b/assets/js/backend_calendar_default_view.js
@@ -66,6 +66,8 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
             $(this).parents('.popover').popover('dispose');
 
             var $dialog;
+            var startDatetime;
+            var endDatetime;
 
             if (lastFocusedEventData.data.is_unavailable === '0') {
                 var appointment = lastFocusedEventData.data;
@@ -80,10 +82,10 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
                 $dialog.find('#select-provider').val(appointment.id_users_provider);
 
                 // Set the start and end datetime of the appointment.
-                var startDatetime = Date.parseExact(appointment.start_datetime, 'yyyy-MM-dd HH:mm:ss');
+                startDatetime = Date.parseExact(appointment.start_datetime, 'yyyy-MM-dd HH:mm:ss');
                 $dialog.find('#start-datetime').datetimepicker('setDate', startDatetime);
 
-                var endDatetime = Date.parseExact(appointment.end_datetime, 'yyyy-MM-dd HH:mm:ss');
+                endDatetime = Date.parseExact(appointment.end_datetime, 'yyyy-MM-dd HH:mm:ss');
                 $dialog.find('#end-datetime').datetimepicker('setDate', endDatetime);
 
                 var customer = appointment.customer;
@@ -103,9 +105,9 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
 
                 // Replace string date values with actual date objects.
                 unavailable.start_datetime = lastFocusedEventData.start.format('YYYY-MM-DD HH:mm:ss');
-                var startDatetime = Date.parseExact(unavailable.start_datetime, 'yyyy-MM-dd HH:mm:ss');
+                startDatetime = Date.parseExact(unavailable.start_datetime, 'yyyy-MM-dd HH:mm:ss');
                 unavailable.end_datetime = lastFocusedEventData.end.format('YYYY-MM-DD HH:mm:ss');
-                var endDatetime = Date.parseExact(unavailable.end_datetime, 'yyyy-MM-dd HH:mm:ss');
+                endDatetime = Date.parseExact(unavailable.end_datetime, 'yyyy-MM-dd HH:mm:ss');
 
                 $dialog = $('#manage-unavailable');
                 BackendCalendarUnavailabilitiesModal.resetUnavailableDialog();
@@ -135,14 +137,14 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
             var url;
             var data;
 
-            // If id_role parameter exists the popover is an extra working day.
+            // If id_role parameter exists the popover is an custom availability period.
             if (lastFocusedEventData.data.hasOwnProperty('id_roles')) {
                 // Do not display confirmation prompt.
-                url = GlobalVariables.baseUrl + '/index.php/backend_api/ajax_delete_extra_period';
+                url = GlobalVariables.baseUrl + '/index.php/backend_api/ajax_delete_custom_availability_period';
 
                 data = {
                     csrfToken: GlobalVariables.csrfToken,
-                    extra_period: lastFocusedEventData.start.format('YYYY-MM-DD'),
+                    custom_availability_period: lastFocusedEventData.start.format('YYYY-MM-DD'),
                     provider_id: lastFocusedEventData.data.id
                 };
 
@@ -150,9 +152,9 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
                     .done(function () {
                         $('#message-box').dialog('close');
 
-                        var extraWorkingPlan = jQuery.parseJSON(lastFocusedEventData.data.settings.extra_working_plan);
-                        delete extraWorkingPlan[lastFocusedEventData.start.format('YYYY-MM-DD')];
-                        lastFocusedEventData.data.settings.extra_working_plan = JSON.stringify(extraWorkingPlan);
+                        var customAvailabilityPeriods = jQuery.parseJSON(lastFocusedEventData.data.settings.custom_availability_periods);
+                        delete customAvailabilityPeriods[lastFocusedEventData.start.format('YYYY-MM-DD')];
+                        lastFocusedEventData.data.settings.custom_availability_periods = JSON.stringify(customAvailabilityPeriods);
 
                         // Refresh calendar event items.
                         $('#select-filter-item').trigger('change');
@@ -295,7 +297,7 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
      * When the user clicks on an appointment object on the calendar, then a data preview popover is display
      * above the calendar item.
      */
-    function calendarEventClick(event, jsEvent, view) {
+    function calendarEventClick(event, jsEvent) {
         $('.popover').popover('dispose'); // Close all open popovers.
 
         var $html;
@@ -385,7 +387,7 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
                     })
                 ]
             });
-        } else if ($(this).hasClass('fc-extra') || $parent.hasClass('fc-extra') || $altParent.hasClass('fc-extra')) {
+        } else if ($(this).hasClass('fc-custom-availability-period') || $parent.hasClass('fc-custom-availability-period') || $altParent.hasClass('fc-custom-availability-period')) {
             displayDelete = (($parent.hasClass('fc-custom') || $altParent.hasClass('fc-custom'))
                 && GlobalVariables.user.privileges.appointments.delete === true)
                 ? 'mr-2' : 'd-none'; // Same value at the time.
@@ -618,7 +620,7 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
      *
      * @see updateAppointmentData()
      */
-    function calendarEventResize(event, delta, revertFunc, jsEvent, ui, view) {
+    function calendarEventResize(event, delta, revertFunc) {
         if (GlobalVariables.user.privileges.appointments.edit === false) {
             revertFunc();
             Backend.displayNotification(EALang.no_privileges_edit_appointments);
@@ -626,6 +628,7 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
         }
 
         var $calendar = $('#calendar');
+        var successCallback;
 
         if ($('#notification').is(':visible')) {
             $('#notification').hide('bind');
@@ -646,7 +649,7 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
             delete appointment.service;
 
             // Success callback
-            var successCallback = function (response) {
+            successCallback = function () {
                 // Display success notification to user.
                 var undoFunction = function () {
                     appointment.end_datetime = event.data.end_datetime = Date.parseExact(
@@ -695,7 +698,7 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
             event.data.end_datetime = unavailable.end_datetime;
 
             // Define success callback function.
-            var successCallback = function (response) {
+            successCallback = function () {
                 // Display success notification to user.
                 var undoFunction = function () {
                     unavailable.end_datetime = event.data.end_datetime = Date.parseExact(
@@ -731,7 +734,7 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
                 $calendar.fullCalendar('updateEvent', event);
             };
 
-            BackendCalendarApi.saveUnavailable(unavailable, successCallback);
+            BackendCalendarApi.saveUnavailable(unavailable, successCallback, null);
         }
     }
 
@@ -743,7 +746,7 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
      *
      * @see getCalendarHeight()
      */
-    function calendarWindowResize(view) {
+    function calendarWindowResize() {
         $('#calendar').fullCalendar('option', 'height', getCalendarHeight());
     }
 
@@ -752,8 +755,10 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
      *
      * When the user clicks on a day square on the calendar, then he will automatically be transferred to that
      * day view calendar.
+     *
+     * @param {Date} date
      */
-    function calendarDayClick(date, jsEvent, view) {
+    function calendarDayClick(date) {
         if (!date.hasTime()) {
             $('#calendar').fullCalendar('changeView', 'agendaDay');
             $('#calendar').fullCalendar('gotoDate', date);
@@ -765,8 +770,12 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
      *
      * This event handler is triggered whenever the user drags and drops an event into a different position
      * on the calendar. We need to update the database with this change. This is done via an ajax call.
+     *
+     * @param {object} event
+     * @param {object} delta
+     * @param {function} revertFunc
      */
-    function calendarEventDrop(event, delta, revertFunc, jsEvent, ui, view) {
+    function calendarEventDrop(event, delta, revertFunc) {
         if (GlobalVariables.user.privileges.appointments.edit === false) {
             revertFunc();
             Backend.displayNotification(EALang.no_privileges_edit_appointments);
@@ -777,6 +786,8 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
             $('#notification').hide('bind');
         }
 
+        var successCallback;
+
         if (event.data.is_unavailable === '0') {
             // Prepare appointment data.
             var appointment = GeneralFunctions.clone(event.data);
@@ -800,7 +811,7 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
             event.data.end_datetime = appointment.end_datetime;
 
             // Define success callback function.
-            var successCallback = function (response) {
+            successCallback = function () {
                 // Define the undo function, if the user needs to reset the last change.
                 var undoFunction = function () {
                     appointment.start_datetime = Date.parseExact(
@@ -852,7 +863,7 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
                 id_users_provider: event.data.id_users_provider
             };
 
-            var successCallback = function (response) {
+            successCallback = function () {
                 var undoFunction = function () {
                     unavailable.start_datetime = Date.parseExact(
                         unavailable.start_datetime, 'yyyy-MM-dd HH:mm:ss')
@@ -993,31 +1004,20 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
                 $calendar.fullCalendar('removeEvents');
                 $calendar.fullCalendar('addEventSource', calendarEvents);
 
-                var weekDays = [
-                    'sunday',
-                    'monday',
-                    'tuesday',
-                    'wednesday',
-                    'thursday',
-                    'friday',
-                    'saturday'
-                ];
-
                 // :: ADD PROVIDER'S UNAVAILABLE TIME PERIODS
                 var calendarView = $calendar.fullCalendar('getView').name;
 
                 if (filterType === FILTER_TYPE_PROVIDER && calendarView !== 'month') {
-                    GlobalVariables.availableProviders.forEach(function (provider, index) {
+                    GlobalVariables.availableProviders.forEach(function (provider) {
                         if (Number(provider.id) === Number(recordId)) {
-                            var workingPlan = {};
-                            var workingPlanBulk = jQuery.parseJSON(provider.settings.working_plan);
-                            var extraWorkingPlan = jQuery.parseJSON(provider.settings.extra_working_plan);
+                            var workingPlan = jQuery.parseJSON(provider.settings.working_plan);
+                            var customAvailabilityPeriods = jQuery.parseJSON(provider.settings.custom_availability_periods);
                             var unavailablePeriod;
 
                             // Sort the working plan starting with the first day as set in General settings to correctly
                             // align breaks in the calendar display.
                             var firstWeekdayNumber = GeneralFunctions.getWeekDayId(GlobalVariables.firstWeekday);
-                            workingPlan = GeneralFunctions.sortWeekDictionary(workingPlanBulk, firstWeekdayNumber);
+                            var sortedWorkingPlan = GeneralFunctions.sortWeekDictionary(workingPlan, firstWeekdayNumber);
 
                             switch (calendarView) {
                                 case 'agendaDay':
@@ -1025,7 +1025,7 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
                                         .getWeekdayName(parseInt($calendar.fullCalendar('getView').start.format('d')));
 
                                     // Add custom unavailable periods.
-                                    response.unavailables.forEach(function (unavailable, index) {
+                                    response.unavailables.forEach(function (unavailable) {
                                         var notes = unavailable.notes ? ' - ' + unavailable.notes : '';
 
                                         if (unavailable.notes.length > 30) {
@@ -1047,28 +1047,28 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
                                     });
 
                                     // Non-working day.
-                                    if (workingPlan[selectedDayName] === null) {
-                                        // Extra working plan day.
+                                    if (sortedWorkingPlan[selectedDayName] === null) {
+                                        // Custom availability period.
                                         var selectedDay = $calendar.fullCalendar('getView').intervalStart.clone();
                                         selectedDay.locale('en');
-                                        if (extraWorkingPlan && selectedDay.format() in extraWorkingPlan) {
-                                            workingPlan[selectedDay.format('dddd').toLowerCase()] = extraWorkingPlan[selectedDay.format('YYYY-MM-DD')];
+                                        if (customAvailabilityPeriods && selectedDay.format() in customAvailabilityPeriods) {
+                                            sortedWorkingPlan[selectedDay.format('dddd').toLowerCase()] = customAvailabilityPeriods[selectedDay.format('YYYY-MM-DD')];
 
-                                            var start_extra = selectedDay.format('YYYY-MM-DD') + ' ' + extraWorkingPlan[selectedDay.format('YYYY-MM-DD')].start;
-                                            var end_extra = selectedDay.format('YYYY-MM-DD') + ' ' + extraWorkingPlan[selectedDay.format('YYYY-MM-DD')].end;
+                                            var customAvailabilityPeriodStart = selectedDay.format('YYYY-MM-DD') + ' ' + customAvailabilityPeriods[selectedDay.format('YYYY-MM-DD')].start;
+                                            var customAvailabilityPeriodEnd = selectedDay.format('YYYY-MM-DD') + ' ' + customAvailabilityPeriods[selectedDay.format('YYYY-MM-DD')].end;
 
-                                            var extraPeriod = {
-                                                title: EALang.extra_period,
-                                                start: moment(start_extra, 'YYYY-MM-DD HH:mm', true),
-                                                end: moment(end_extra, 'YYYY-MM-DD HH:mm', true).add(1, 'day'),
+                                            var customAvailabilityPeriod = {
+                                                title: EALang.custom_availability_period,
+                                                start: moment(customAvailabilityPeriodStart, 'YYYY-MM-DD HH:mm', true),
+                                                end: moment(customAvailabilityPeriodEnd, 'YYYY-MM-DD HH:mm', true).add(1, 'day'),
                                                 allDay: true,
                                                 color: '#879DB4',
                                                 editable: false,
-                                                className: 'fc-extra fc-custom',
+                                                className: 'fc-custom-availability-period fc-custom',
                                                 data: provider
                                             };
 
-                                            $calendar.fullCalendar('renderEvent', extraPeriod, false);
+                                            $calendar.fullCalendar('renderEvent', customAvailabilityPeriod, false);
                                         } else {
                                             unavailablePeriod = {
                                                 title: EALang.not_working,
@@ -1088,7 +1088,7 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
 
                                     // Add unavailable period before work starts.
                                     var calendarDateStart = moment($calendar.fullCalendar('getView').start.format('YYYY-MM-DD') + ' 00:00:00');
-                                    var startHour = workingPlan[selectedDayName].start.split(':');
+                                    var startHour = sortedWorkingPlan[selectedDayName].start.split(':');
                                     var workDateStart = calendarDateStart.clone();
                                     workDateStart.hour(parseInt(startHour[0]));
                                     workDateStart.minute(parseInt(startHour[1]));
@@ -1108,7 +1108,7 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
 
                                     // Add unavailable period after work ends.
                                     var calendarDateEnd = moment($calendar.fullCalendar('getView').end.format('YYYY-MM-DD') + ' 00:00:00');
-                                    var endHour = workingPlan[selectedDayName].end.split(':');
+                                    var endHour = sortedWorkingPlan[selectedDayName].end.split(':');
                                     var workDateEnd = calendarDateStart.clone();
 
                                     workDateEnd.hour(parseInt(endHour[0]));
@@ -1132,7 +1132,7 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
                                     var breakStart;
                                     var breakEnd;
 
-                                    workingPlan[selectedDayName].breaks.forEach(function (currentBreak) {
+                                    sortedWorkingPlan[selectedDayName].breaks.forEach(function (currentBreak) {
                                         var breakStartString = currentBreak.start.split(':');
                                         breakStart = calendarDateStart.clone();
                                         breakStart.hour(parseInt(breakStartString[0]));
@@ -1185,27 +1185,27 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
                                         $calendar.fullCalendar('renderEvent', unavailablePeriod, false);
                                     });
 
-                                    $.each(workingPlan, function (index, workingDay) {
+                                    $.each(sortedWorkingPlan, function (index, workingDay) {
                                         if (workingDay === null) {
-                                            // Check if the day is an extra working day added to the working plan
-                                            if (extraWorkingPlan && currentDateStart.format('YYYY-MM-DD') in extraWorkingPlan) {
-                                                workingDay = extraWorkingPlan[currentDateStart.format('YYYY-MM-DD')]
+                                            // Check if the day is an custom availability period added to the working plan
+                                            if (customAvailabilityPeriods && currentDateStart.format('YYYY-MM-DD') in customAvailabilityPeriods) {
+                                                workingDay = customAvailabilityPeriods[currentDateStart.format('YYYY-MM-DD')]
 
-                                                var extraPeriodStart = currentDateStart.format('YYYY-MM-DD') + ' ' + extraWorkingPlan[currentDateStart.format('YYYY-MM-DD')].start;
-                                                var extraPeriodEnd = currentDateStart.format('YYYY-MM-DD') + ' ' + extraWorkingPlan[currentDateStart.format('YYYY-MM-DD')].end;
+                                                var customAvailabilityPeriodStart = currentDateStart.format('YYYY-MM-DD') + ' ' + customAvailabilityPeriods[currentDateStart.format('YYYY-MM-DD')].start;
+                                                var customAvailabilityPeriodEnd = currentDateStart.format('YYYY-MM-DD') + ' ' + customAvailabilityPeriods[currentDateStart.format('YYYY-MM-DD')].end;
 
-                                                var extraPeriod = {
-                                                    title: EALang.extra_period,
-                                                    start: moment(extraPeriodStart, 'YYYY-MM-DD HH:mm', true),
-                                                    end: moment(extraPeriodEnd, 'YYYY-MM-DD HH:mm', true).add(1, 'day'),
+                                                var customAvailabilityPeriod = {
+                                                    title: EALang.custom_woring_period,
+                                                    start: moment(customAvailabilityPeriodStart, 'YYYY-MM-DD HH:mm', true),
+                                                    end: moment(customAvailabilityPeriodEnd, 'YYYY-MM-DD HH:mm', true).add(1, 'day'),
                                                     allDay: true,
                                                     color: '#879DB4',
                                                     editable: false,
-                                                    className: 'fc-extra fc-custom',
+                                                    className: 'fc-custom-availability-period fc-custom',
                                                     data: provider
                                                 };
 
-                                                $calendar.fullCalendar('renderEvent', extraPeriod, false);
+                                                $calendar.fullCalendar('renderEvent', customAvailabilityPeriod, false);
                                             } else {
                                                 // Add a full day unavailable event.
                                                 unavailablePeriod = {
@@ -1273,7 +1273,7 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
                                         var breakStart;
                                         var breakEnd;
 
-                                        workingDay.breaks.forEach(function (currentBreak, index) {
+                                        workingDay.breaks.forEach(function (currentBreak) {
                                             var breakStartString = currentBreak.start.split(':');
                                             breakStart = currentDateStart.clone();
                                             breakStart.hour(parseInt(breakStartString[0]));
@@ -1375,7 +1375,7 @@ window.BackendCalendarDefaultView = window.BackendCalendarDefaultView || {};
             // Selectable
             selectable: true,
             selectHelper: true,
-            select: function (start, end, jsEvent, view) {
+            select: function (start, end) {
                 if (!start.hasTime() || !end.hasTime()) {
                     return;
                 }
diff --git a/assets/js/backend_calendar_table_view.js b/assets/js/backend_calendar_table_view.js
index d4d98825..89a10c15 100755
--- a/assets/js/backend_calendar_table_view.js
+++ b/assets/js/backend_calendar_table_view.js
@@ -71,7 +71,7 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
             var endDate = endDateMoment.toDate();
 
             getCalendarEvents(startDate, endDate)
-                .done(function (response) {
+                .done(function () {
                     var currentDate = startDate;
 
                     while (currentDate <= endDate) {
@@ -89,22 +89,22 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
                                 var $providerColumn = $(providerColumn);
                                 var provider = $providerColumn.data('provider');
 
-                                // $providerColumn.find('.calendar-wrapper').fullCalendar('removeEvents');
+                                $providerColumn.find('.calendar-wrapper').fullCalendar('removeEvents');
 
-                                // createNonWorkingHours($providerColumn.find('.calendar-wrapper'), JSON.parse($providerColumn.data('provider').settings.working_plan));
+                                createNonWorkingHours($providerColumn.find('.calendar-wrapper'), JSON.parse($providerColumn.data('provider').settings.working_plan));
 
                                 // Add the appointments to the column.
-                                // createAppointments($providerColumn, response.appointments);
+                                createAppointments($providerColumn, response.appointments);
 
                                 // Add the unavailabilities to the column.
-                                // createUnavailabilities($providerColumn, response.unavailabilities);
+                                createUnavailabilities($providerColumn, response.unavailabilities);
 
                                 // Add the provider breaks to the column.
                                 var workingPlan = JSON.parse(provider.settings.working_plan);
                                 var day = date.toString('dddd').toLowerCase();
                                 if (workingPlan[day]) {
                                     var breaks = workingPlan[day].breaks;
-                                    // createBreaks($providerColumn, breaks);
+                                    createBreaks($providerColumn, breaks);
                                 }
                             });
                         });
@@ -213,24 +213,24 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
             var url;
             var data;
 
-            // If id_role parameter exists the popover is an extra working day.
+            // If id_role parameter exists the popover is an custom availability period.
             if (lastFocusedEventData.data.hasOwnProperty('id_roles')) {
                 // Do not display confirmation prompt.
-                url = GlobalVariables.baseUrl + '/index.php/backend_api/ajax_delete_extra_period';
+                url = GlobalVariables.baseUrl + '/index.php/backend_api/ajax_delete_custom_availability_period';
 
                 data = {
                     csrfToken: GlobalVariables.csrfToken,
-                    extra_period: lastFocusedEventData.start.format('YYYY-MM-DD'),
+                    custom_availability_period: lastFocusedEventData.start.format('YYYY-MM-DD'),
                     provider_id: lastFocusedEventData.data.id
                 };
 
                 $.post(url, data)
-                    .done(function (response) {
+                    .done(function () {
                         $('#message-box').dialog('close');
 
-                        var extraWorkingPlan = jQuery.parseJSON(lastFocusedEventData.data.settings.extra_working_plan);
-                        delete extraWorkingPlan[lastFocusedEventData.start.format('YYYY-MM-DD')];
-                        lastFocusedEventData.data.settings.extra_working_plan = JSON.stringify(extraWorkingPlan);
+                        var customAvailabilityPeriods = jQuery.parseJSON(lastFocusedEventData.data.settings.custom_availability_periods);
+                        delete customAvailabilityPeriods[lastFocusedEventData.start.format('YYYY-MM-DD')];
+                        lastFocusedEventData.data.settings.custom_availability_periods = JSON.stringify(customAvailabilityPeriods);
 
                         // Refresh calendar event items.
                         $('#select-filter-item').trigger('change');
@@ -329,7 +329,7 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
         $('<input/>', {
             'type': 'text',
             'class': 'form-control d-inline-block select-date mr-2',
-            'value': GeneralFunctions.formatDate(new Date(), GlobalVariables.dateFormat)
+            'value': GeneralFunctions.formatDate(new Date(), GlobalVariables.dateFormat, false)
         })
             .appendTo($calendarHeader);
 
@@ -359,7 +359,7 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
                 break;
 
             default:
-                throw new Error('Invalid date format setting provided!', GlobalVariables.dateFormat);
+                throw new Error('Invalid date format setting provided: ' + GlobalVariables.dateFormat);
         }
 
         $calendarHeader.find('.select-date').datepicker({
@@ -677,7 +677,7 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
             // Selectable
             selectable: true,
             selectHelper: true,
-            select: function (start, end, jsEvent, view) {
+            select: function (start, end, jsEvent) {
                 if (!start.hasTime() || !end.hasTime()) {
                     return;
                 }
@@ -850,7 +850,7 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
         var breakStart;
         var breakEnd;
 
-        workingPlan[selDayName].breaks.forEach(function (currentBreak, index) {
+        workingPlan[selDayName].breaks.forEach(function (currentBreak) {
             breakStart = moment(start.toDate().toString('yyyy-MM-dd') + ' ' + currentBreak.start);
             breakEnd = moment(start.toDate().toString('yyyy-MM-dd') + ' ' + currentBreak.end);
 
@@ -1109,19 +1109,15 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
                     })
                 ]
             });
-        } else if ($(this).hasClass('fc-extra') || $parent.hasClass('fc-extra') || $altParent.hasClass('fc-extra')) {
+        } else if ($(this).hasClass('fc-custom-availability-period') || $parent.hasClass('fc-custom-availability-period') || $altParent.hasClass('fc-custom-availability-period')) {
+            displayEdit = (($parent.hasClass('fc-custom') || $altParent.hasClass('fc-custom'))
+                && GlobalVariables.user.privileges.appointments.edit === true)
+                ? 'mr-2' : 'd-none'; // Same value at the time.
+
             displayDelete = (($parent.hasClass('fc-custom') || $altParent.hasClass('fc-custom'))
                 && GlobalVariables.user.privileges.appointments.delete === true)
                 ? 'mr-2' : 'd-none'; // Same value at the time.
 
-            var provider = '';
-
-            if (event.data) { // Only custom unavailable periods have notes.
-                provider = '<strong>' + EALang.provider + '</strong> ' + event.data.first_name + ' ' + event.data.last_name;
-            }
-
-            var extraPeriod = jQuery.parseJSON(event.data.settings.extra_working_plan)[event.start.format()];
-
             $html = $('<div/>', {
                 'html': [
                     $('<strong/>', {
@@ -1353,7 +1349,7 @@ window.BackendCalendarTableView = window.BackendCalendarTableView || {};
      *
      * @see updateAppointmentData()
      */
-    function onEventResize(event, delta, revertFunc, jsEvent, ui, view) {
+    function onEventResize(event, delta, revertFunc) {
         if (GlobalVariables.user.privileges.appointments.edit === false) {
             revertFunc();
             Backend.displayNotification(EALang.no_privileges_edit_appointments);
diff --git a/assets/js/backend_users_providers.js b/assets/js/backend_users_providers.js
index 6d474200..f15746b1 100755
--- a/assets/js/backend_users_providers.js
+++ b/assets/js/backend_users_providers.js
@@ -86,7 +86,7 @@
             $('#providers .save-cancel-group').show();
             $('#providers .record-details').find('input, select, textarea').prop('disabled', false);
             $('#provider-password, #provider-password-confirm').addClass('required');
-            $('#providers').find('.add-break, .edit-break, .delete-break, .add-extra-periods, .edit-extra, .delete-extra, #reset-working-plan').prop('disabled', false);
+            $('#providers').find('.add-break, .edit-break, .delete-break, .add-custom-availability-periods, .edit-custom-availability-period, .delete-custom-availability-period, #reset-working-plan').prop('disabled', false);
             $('#provider-services input:checkbox').prop('disabled', false);
 
             // Apply default working plan
@@ -105,7 +105,7 @@
             $('#providers .record-details').find('input, select, textarea').prop('disabled', false);
             $('#provider-password, #provider-password-confirm').removeClass('required');
             $('#provider-services input:checkbox').prop('disabled', false);
-            $('#providers').find('.add-break, .edit-break, .delete-break, .add-extra-periods, .edit-extra, .delete-extra, #reset-working-plan').prop('disabled', false);
+            $('#providers').find('.add-break, .edit-break, .delete-break, .add-custom-availability-periods, .edit-custom-availability-period, .delete-custom-availability-period, #reset-working-plan').prop('disabled', false);
             $('#providers input:checkbox').prop('disabled', false);
             BackendUsers.wp.timepickers(false);
         });
@@ -154,7 +154,7 @@
                 settings: {
                     username: $('#provider-username').val(),
                     working_plan: JSON.stringify(BackendUsers.wp.get()),
-                    extra_working_plan: JSON.stringify(BackendUsers.wp.getExtraWP()),
+                    custom_availability_periods: JSON.stringify(BackendUsers.wp.getCustomavailabilityperiods()),
                     notifications: $('#provider-notifications').prop('checked'),
                     calendar_view: $('#provider-calendar-view').val()
                 }
@@ -210,7 +210,7 @@
          */
         $('#providers').on('click', '#reset-working-plan', function () {
             $('.breaks tbody').empty();
-            $('.extra-periods tbody').empty();
+            $('.custom-availability-periods tbody').empty();
             $('.work-start, .work-end').val('');
             BackendUsers.wp.setup(GlobalVariables.workingPlan);
             BackendUsers.wp.timepickers(false);
@@ -333,12 +333,12 @@
         $('#providers .record-details').find('input, select, textarea')
             .val('')
             .prop('disabled', true);
-        $('#providers .add-break, .add-extra-periods, #reset-working-plan').prop('disabled', true);
+        $('#providers .add-break, .add-custom-availability-periods, #reset-working-plan').prop('disabled', true);
         BackendUsers.wp.timepickers(true);
         $('#providers .working-plan input:text').timepicker('destroy');
         $('#providers .working-plan input:checkbox').prop('disabled', true);
         $('.breaks').find('.edit-break, .delete-break').prop('disabled', true);
-        $('.extra-periods').find('.edit-extra, .delete-extra').prop('disabled', true);
+        $('.custom-availability-periods').find('.edit-custom-availability-period, .delete-custom-availability-period').prop('disabled', true);
 
         $('#providers .record-details .has-error').removeClass('has-error');
         $('#providers .record-details .form-message').hide();
@@ -350,7 +350,7 @@
         $('#provider-services a').remove();
         $('#providers .working-plan tbody').empty();
         $('#providers .breaks tbody').empty();
-        $('#providers .extra-periods tbody').empty();
+        $('#providers .custom-availability-periods tbody').empty();
     };
 
     /**
@@ -426,10 +426,10 @@
         BackendUsers.wp.setup(workingPlan);
         $('.working-plan').find('input').prop('disabled', true);
         $('.breaks').find('.edit-break, .delete-break').prop('disabled', true);
-        $('#providers .extra-periods tbody').empty();
-        var extraWorkingPlan = $.parseJSON(provider.settings.extra_working_plan);
-        BackendUsers.wp.setupExtraPeriods(extraWorkingPlan);
-        $('.extra-periods').find('.edit-extra, .delete-extra').prop('disabled', true);
+        $('#providers .custom-availability-periods tbody').empty();
+        var customAvailabilityPeriods = $.parseJSON(provider.settings.custom_availability_periods);
+        BackendUsers.wp.setupcustomAvailabilityPeriods(customAvailabilityPeriods);
+        $('.custom-availability-periods').find('.edit-custom-availability-period, .delete-custom-availability-period').prop('disabled', true);
         $('#providers .working-plan input:checkbox').prop('disabled', true);
         Backend.placeFooterToBottom();
     };
diff --git a/assets/js/working_plan.js b/assets/js/working_plan.js
index 6cf88541..2a5adfe4 100755
--- a/assets/js/working_plan.js
+++ b/assets/js/working_plan.js
@@ -188,16 +188,16 @@
     };
 
     /**
-     * Setup the dom elements of a given extra working plan day.
+     * Setup the dom elements of a given Custom availability period.
      *
-     * @param {Object} extraWorkingPlan Contains the extra working day.
+     * @param {Object} customAvailabilityPeriods Contains the custom availability period.
      */
-    WorkingPlan.prototype.setupExtraPeriods = function (extraWorkingPlan) {
-        $.each(extraWorkingPlan, function (index, extraWorkingDay) {
-            if (extraWorkingDay) {
+    WorkingPlan.prototype.setupcustomAvailabilityPeriods = function (customAvailabilityPeriods) {
+        $.each(customAvailabilityPeriods, function (index, customAvailabilityPeriod) {
+            if (customAvailabilityPeriod) {
                 $('#' + index).prop('checked', true);
-                $('#' + index + '-start').val(Date.parse(extraWorkingDay.start).toString(GlobalVariables.timeFormat === 'regular' ? 'h:mm tt' : 'HH:mm').toUpperCase());
-                $('#' + index + '-end').val(Date.parse(extraWorkingDay.end).toString(GlobalVariables.timeFormat === 'regular' ? 'h:mm tt' : 'HH:mm').toUpperCase());
+                $('#' + index + '-start').val(Date.parse(customAvailabilityPeriod.start).toString(GlobalVariables.timeFormat === 'regular' ? 'h:mm tt' : 'HH:mm').toUpperCase());
+                $('#' + index + '-end').val(Date.parse(customAvailabilityPeriod.end).toString(GlobalVariables.timeFormat === 'regular' ? 'h:mm tt' : 'HH:mm').toUpperCase());
 
                 var day = GeneralFunctions.formatDate(Date.parse(index), GlobalVariables.dateFormat, false);
 
@@ -206,22 +206,22 @@
                 $('<tr/>', {
                     'html': [
                         $('<td/>', {
-                            'class': 'extra-day editable',
+                            'class': 'custom-availability-period editable',
                             'text': day
                         }),
                         $('<td/>', {
-                            'class': 'extra-start editable',
-                            'text': Date.parse(extraWorkingDay.start).toString(timeFormat).toUpperCase()
+                            'class': 'custom-availability-period-start editable',
+                            'text': Date.parse(customAvailabilityPeriod.start).toString(timeFormat).toUpperCase()
                         }),
                         $('<td/>', {
-                            'class': 'extra-end editable',
-                            'text': Date.parse(extraWorkingDay.end).toString(timeFormat).toUpperCase()
+                            'class': 'custom-availability-period-end editable',
+                            'text': Date.parse(customAvailabilityPeriod.end).toString(timeFormat).toUpperCase()
                         }),
                         $('<td/>', {
                             'html': [
                                 $('<button/>', {
                                     'type': 'button',
-                                    'class': 'btn btn-light btn-sm edit-extra',
+                                    'class': 'btn btn-light btn-sm edit-custom-availability-period',
                                     'title': EALang.edit,
                                     'html': [
                                         $('<span/>', {
@@ -231,7 +231,7 @@
                                 }),
                                 $('<button/>', {
                                     'type': 'button',
-                                    'class': 'btn btn-light btn-sm delete-extra',
+                                    'class': 'btn btn-light btn-sm delete-custom-availability-period',
                                     'title': EALang.delete,
                                     'html': [
                                         $('<span/>', {
@@ -241,7 +241,7 @@
                                 }),
                                 $('<button/>', {
                                     'type': 'button',
-                                    'class': 'btn btn-light btn-sm save-extra d-none',
+                                    'class': 'btn btn-light btn-sm save-custom-availability-period d-none',
                                     'title': EALang.save,
                                     'html': [
                                         $('<span/>', {
@@ -251,7 +251,7 @@
                                 }),
                                 $('<button/>', {
                                     'type': 'button',
-                                    'class': 'btn btn-light btn-sm cancel-extra d-none',
+                                    'class': 'btn btn-light btn-sm cancel-custom-availability-period d-none',
                                     'title': EALang.cancel,
                                     'html': [
                                         $('<span/>', {
@@ -263,7 +263,7 @@
                         })
                     ]
                 })
-                    .appendTo('.extra-periods tbody');
+                    .appendTo('.custom-availability-periods tbody');
             } else {
                 $('#' + index).prop('checked', false);
                 $('#' + index + '-start').prop('disabled', true);
@@ -272,8 +272,8 @@
         }.bind(this));
 
         // Make break cells editable.
-        this.editableBreakTime($('.extra-periods .extra-day'));
-        this.editableBreakTime($('.extra-periods').find('.extra-start, .extra-end'));
+        this.editableBreakTime($('.custom-availability-periods .custom-availability-period'));
+        this.editableBreakTime($('.custom-availability-periods').find('.custom-availability-period-start, .custom-availability-period-end'));
     };
 
     /**
@@ -554,33 +554,33 @@
         }.bind(this));
 
         /**
-         * Event: Add Extra Period Button "Click"
+         * Event: Add custom availability period Button "Click"
          *
-         * A new row is added on the table and the user can enter the new extra day
-         * data. After that he can either press the save or cancel button.
+         * A new row is added on the table and the user can enter the new custom availability period. After that he can
+         * either press the save or cancel button.
          */
-        $('.add-extra-periods').on('click', function () {
+        $('.add-custom-availability-periods').on('click', function () {
             var today = GeneralFunctions.formatDate(new Date(), GlobalVariables.dateFormat, false);
 
-            var $newExtraPeriod = $('<tr/>', {
+            var $newcustomAvailabilityPeriod = $('<tr/>', {
                 'html': [
                     $('<td/>', {
-                        'class': 'extra-day editable',
+                        'class': 'custom-availability-period editable',
                         'text': today
                     }),
                     $('<td/>', {
-                        'class': 'extra-start editable',
+                        'class': 'custom-availability-period-start editable',
                         'text': '9:00 AM'
                     }),
                     $('<td/>', {
-                        'class': 'extra-end editable',
+                        'class': 'custom-availability-period-end editable',
                         'text': '10:00 AM'
                     }),
                     $('<td/>', {
                         'html': [
                             $('<button/>', {
                                 'type': 'button',
-                                'class': 'btn btn-light btn-sm edit-extra',
+                                'class': 'btn btn-light btn-sm edit-custom-availability-period',
                                 'title': EALang.edit,
                                 'html': [
                                     $('<span/>', {
@@ -590,7 +590,7 @@
                             }),
                             $('<button/>', {
                                 'type': 'button',
-                                'class': 'btn btn-light btn-sm delete-extra',
+                                'class': 'btn btn-light btn-sm delete-custom-availability-period',
                                 'title': EALang.delete,
                                 'html': [
                                     $('<span/>', {
@@ -600,7 +600,7 @@
                             }),
                             $('<button/>', {
                                 'type': 'button',
-                                'class': 'btn btn-light btn-sm save-extra d-none',
+                                'class': 'btn btn-light btn-sm save-custom-availability-period d-none',
                                 'title': EALang.save,
                                 'html': [
                                     $('<span/>', {
@@ -610,7 +610,7 @@
                             }),
                             $('<button/>', {
                                 'type': 'button',
-                                'class': 'btn btn-light btn-sm cancel-extra d-none',
+                                'class': 'btn btn-light btn-sm cancel-custom-availability-period d-none',
                                 'title': EALang.cancel,
                                 'html': [
                                     $('<span/>', {
@@ -622,21 +622,21 @@
                     }),
                 ]
             })
-                .appendTo('.extra-periods tbody');
+                .appendTo('.custom-availability-periods tbody');
 
             // Bind editable and event handlers.
-            this.editableBreakTime($newExtraPeriod.find('.extra-day'));
-            this.editableBreakTime($newExtraPeriod.find('.extra-start, .extra-end'));
-            $newExtraPeriod.find('.edit-extra').trigger('click');
-            $('.add-extra-periods').prop('disabled', true);
+            this.editableBreakTime($newcustomAvailabilityPeriod.find('.custom-availability-period'));
+            this.editableBreakTime($newcustomAvailabilityPeriod.find('.custom-availability-period-start, .custom-availability-period-end'));
+            $newcustomAvailabilityPeriod.find('.edit-custom-availability-period').trigger('click');
+            $('.add-custom-availability-periods').prop('disabled', true);
         }.bind(this));
 
         /**
-         * Event: Edit Extra Period Button "Click"
+         * Event: Edit custom availability period Button "Click"
          *
-         * Enables the row editing for the "Extra Period" table rows.
+         * Enables the row editing for the "custom availability period" table rows.
          */
-        $(document).on('click', '.edit-extra', function () {
+        $(document).on('click', '.edit-custom-availability-period', function () {
             // Reset previous editable table cells.
             var $previousEdits = $(this).closest('table').find('.editable');
 
@@ -648,7 +648,7 @@
 
             // Make all cells in current row editable.
             $(this).parent().parent().children().trigger('edit');
-            $(this).parent().parent().find('.extra-start input, .extra-end input').timepicker({
+            $(this).parent().parent().find('.custom-availability-period-start input, .custom-availability-period-end input').timepicker({
                 timeFormat: GlobalVariables.timeFormat === 'regular' ? 'h:mm TT' : 'HH:mm',
                 currentText: EALang.now,
                 closeText: EALang.close,
@@ -672,7 +672,7 @@
                     break;
             }
 
-            $(this).parent().parent().find('.extra-day input').datetimepicker({
+            $(this).parent().parent().find('.custom-availability-period input').datetimepicker({
                 dateFormat: dateFormat,
 
                 // Translation
@@ -699,66 +699,66 @@
 
             // Show save - cancel buttons.
             var $tr = $(this).closest('tr');
-            $tr.find('.edit-extra, .delete-extra').addClass('d-none');
-            $tr.find('.save-extra, .cancel-extra').removeClass('d-none');
+            $tr.find('.edit-custom-availability-period, .delete-custom-availability-period').addClass('d-none');
+            $tr.find('.save-custom-availability-period, .cancel-custom-availability-period').removeClass('d-none');
             $tr.find('select,input:text').addClass('form-control input-sm')
 
-            $('.add-extra-periods').prop('disabled', true);
+            $('.add-custom-availability-periods').prop('disabled', true);
         });
 
         /**
-         * Event: Delete Extra Period Button "Click"
+         * Event: Delete custom availability period Button "Click"
          *
-         * Removes the current line from the "Extra Periods" table.
+         * Removes the current line from the "custom availability periods" table.
          */
-        $(document).on('click', '.delete-extra', function () {
+        $(document).on('click', '.delete-custom-availability-period', function () {
             $(this).parent().parent().remove();
         });
 
         /**
-         * Event: Cancel Extra Period Button "Click"
+         * Event: Cancel custom availability period Button "Click"
          *
-         * Bring the ".extra-period" table back to its initial state.
+         * Bring the ".custom-availability-period" table back to its initial state.
          *
          * @param {jQuery.Event} e
          */
-        $(document).on('click', '.cancel-extra', function (event) {
+        $(document).on('click', '.cancel-custom-availability-period', function (event) {
             var element = event.target;
             var $modifiedRow = $(element).closest('tr');
             this.enableCancel = true;
             $modifiedRow.find('.cancel-editable').trigger('click');
             this.enableCancel = false;
 
-            $(element).closest('table').find('.edit-extra, .delete-extra').removeClass('d-none');
-            $modifiedRow.find('.save-extra, .cancel-extra').addClass('d-none');
-            $('.add-extra-periods').prop('disabled', false);
+            $(element).closest('table').find('.edit-custom-availability-period, .delete-custom-availability-period').removeClass('d-none');
+            $modifiedRow.find('.save-custom-availability-period, .cancel-custom-availability-period').addClass('d-none');
+            $('.add-custom-availability-periods').prop('disabled', false);
         }.bind(this));
 
         /**
-         * Event: Save Extra Period Button "Click"
+         * Event: Save custom availability period Button "Click"
          *
          * Save the editable values and restore the table to its initial state.
          *
          * @param {jQuery.Event} e
          */
-        $(document).on('click', '.save-extra', function (event) {
+        $(document).on('click', '.save-custom-availability-period', function (event) {
             // Break's start time must always be prior to break's end.
             var element = event.target;
             var $modifiedRow = $(element).closest('tr');
-            var start = Date.parse($modifiedRow.find('.extra-start input').val());
-            var end = Date.parse($modifiedRow.find('.extra-end input').val());
+            var start = Date.parse($modifiedRow.find('.custom-availability-period-start input').val());
+            var end = Date.parse($modifiedRow.find('.custom-availability-period-end input').val());
 
             if (start > end) {
-                $modifiedRow.find('.extra-end input').val(start.addHours(1).toString(GlobalVariables.timeFormat === 'regular' ? 'h:mm tt' : 'HH:mm').toUpperCase());
+                $modifiedRow.find('.custom-availability-period-end input').val(start.addHours(1).toString(GlobalVariables.timeFormat === 'regular' ? 'h:mm tt' : 'HH:mm').toUpperCase());
             }
 
             this.enableSubmit = true;
             $modifiedRow.find('.editable .submit-editable').trigger('click');
             this.enableSubmit = false;
 
-            $modifiedRow.find('.save-extra, .cancel-extra').addClass('d-none');
-            $(element).closest('table').find('.edit-extra, .delete-extra').removeClass('d-none');
-            $('.add-extra-periods').prop('disabled', false);
+            $modifiedRow.find('.save-custom-availability-period, .cancel-custom-availability-period').addClass('d-none');
+            $(element).closest('table').find('.edit-custom-availability-period, .delete-custom-availability-period').removeClass('d-none');
+            $('.add-custom-availability-periods').prop('disabled', false);
         }.bind(this));
     };
 
@@ -806,27 +806,27 @@
     };
 
     /**
-     * Get the extra working plan settings.
+     * Get the custom availability periods settings.
      *
-     * @return {Object} Returns the extra working plan settings object.
+     * @return {Object} Returns the custom availability periods settings object.
      */
-    WorkingPlan.prototype.getExtraWP = function () {
-        var extraWorkingPlan = {};
-        $('.extra-periods tbody tr').each(function (index, tr) {
+    WorkingPlan.prototype.getCustomavailabilityperiods = function () {
+        var customAvailabilityPeriods = {};
+        $('.custom-availability-periods tbody tr').each(function (index, tr) {
 
-            var day = GeneralFunctions.ISO8601DateString($(tr).find('.extra-day').text(), GlobalVariables.dateFormat);
+            var day = GeneralFunctions.ISO8601DateString($(tr).find('.custom-availability-period').text(), GlobalVariables.dateFormat);
 
-            var start = $(tr).find('.extra-start').text();
-            var end = $(tr).find('.extra-end').text();
+            var start = $(tr).find('.custom-availability-period-start').text();
+            var end = $(tr).find('.custom-availability-period-end').text();
 
-            extraWorkingPlan[day] = {
+            customAvailabilityPeriods[day] = {
                 start: Date.parse(start).toString('HH:mm'),
                 end: Date.parse(end).toString('HH:mm'),
                 breaks: []
             };
         }.bind(this));
 
-        return extraWorkingPlan;
+        return customAvailabilityPeriods;
     };
 
     /**