CI User Defined Method: Unsupported API parameter type: record

I've created a Component Interface User Defined Method that is passed a record type. I get the following error:

Begin validating Component Interface integrity - DEPARTMENT_TBL

  ** Unsupported API parameter type in function hyCopyRecord, parameter rec

  ***** Found error *****

  Please review Component Interface structure.

End Component Interface validation - DEPARTMENT_TBL

Are there argument or return type limitations?

I've checked the documentation and see no mention of what types are allowable. It doesn't complain if I use basic data types like string, integer, etc. This is my first time experimenting with User Defined Methods.

Rationale:

We want to create a new Department record based on an old record, so the intention here is to setup the new record and just copy it into the underlying component buffer. Obviously, there are other ways to solve the problem and we have working code that just does direct assignment field by field in the CI code. However, my obsessive/compulsive behavior has been aroused.