from VFP HElp

Returning a Value From a Form
You can use forms throughout your application to allow users to specify a value.

To return a value from a form

Set the WindowType property of the form to 1 to make the form modal.
In the code associated with the Unload event of the form, include a RETURN command with the return value.
In the program or method that runs the form, include the TO keyword in the DO FORM command.
For example, if FindCustID is a modal form that returns a character value, the following line of code stores the return value to a variable named cCustID:

DO FORM FindCustID TO cCustID
For more information, see RETURN and DO FORM.

Note If you get an error, make sure the WindowType is set to 1 (Modal).