set_category
Description:
Sets the category of this notification.
This can be used by the notification server to filter or display the data in a certain way.
Parameters:
| this | 
           The notification.  | 
      
| category | 
           The category.  | 
      
Sets the category of this notification.
This can be used by the notification server to filter or display the data in a certain way.
| this | 
           The notification.  | 
      
| category | 
           The category.  |