WSDL: http://xyz.example.com/__/webservices/calendar?wsdl
    
 This web service is used to retrieve calendar events. 
 Argument 1: Module_Calendar_Webservices_Options_GetCategories
                
 The options to determine which categories to return 
 Returns: Array of Module_Calendar_Webservices_Category
                
 This method returns a list of event categories based on the specified options.