Get a list of Programme Types that contain at least one waitlistable Programme. 

This is an authenticated listing of all active Programme Types that contain at least one active programme that is allowed to have a waitlist. 

Each Programme Type is represented by a TPrgt. The collection of Programmes Types is represented by a List of TPrgt. 

A token is passed for authentication. If the authentication fails, or other errors occur, no programmes are returned. The result of the authentication is represented by a TAuthenticate object. 

Requires a valid registration key entry for the Short Courses feature. 

This function has security level "Unrestricted", and can be accessed by any authenticated user.

[WebMethod(Description = "Gets a list of all programme types that contain at least one waitlistable programme")]
public TAuthPrgtList GetWaitlistProgrammeTypes(string token);