Retrieves definitions for the additional fields available for an entity. Each field is represented by a FieldDefinition. The returned TAuthFieldList contains a list of FieldDefinition. 

Additional data can be retrieved for existing records using QueryAdditionalData. 

For an online enrolment, additional data can be set for a web client or web company using UpdateAdditionalDataForWebRecord. 

Additional data can be set for an existing client or employer using UpdateClientAdditionalFields or UpdateEmployerAdditionalFields, respectively. 

The entityName parameter is the name of an entity to get the additional field definitions for. Get a list of entity names from QueryAdditionalData. Note that only fields in the "Client" or "Employer" entity names are valid when updating additional data. All entities are valid when retrieving additional data. 

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

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

[WebMethod(Description = "Gets a list of all fields available to be set for an entity")]
public TAuthFieldList GetAdditionalDataFieldsForEntity(string token, string entityName);