Passing values to/from procedures

I understand how to send parameters to a procedure when I call it and also how to retrive them in that called procedure. How do I retrive values that are returned with the setparameter statement?

If you are going to pass a value back with setparameter, the parameter in question needs to be a field or variable. SetParameter will be setting the value of the field or variable. After the call statement, the calling procedure can simply expect to find the value in the field or variable.

Local sending, receiving
sending = "some value"
call "My Procedure", sending, receiving
message receiving

My Procedure would have contained a statement like

setparameter 2, theresult