Is there a limit to the number of fields that can be fetched in selectColumns of GetSearchRecords?

Is there a limit to the number of fields that can be fetched in selectColumns of GetSearchRecords?

Instead of using selectColumns=Contacts(All), I have opted to manually list all the fields that I require to be fetched by the function GetSearchRecords i.e. selectColumns=Contacts(First Name, Last Name, Email,....etc).  However, it seems that the maximum number of fields that can be selected is 12. 

I have not read anywhere that there is a limit to the number of fields that can be selected by selectColumns.  Can you confirm whether such a limit exists?

Thanks,

Doug Peng
Canada