Thanks! AVFP has this architecture:

ASP/ASP.NET
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Proxystub.prg - subclasses ActiveVFP(so it uses the error handler from there),creates ActiveVFP objects, calls main.prg. has this code after main.prg is called:
SET PROCEDURE TO
CLEAR PROGRAM main
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Main.prg - externally marked, main application code (this is the one that needs to be unloaded), uses ActiveVFP objects
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Activevfp.prg - contains the various classes
has this code in the error handler:
SET PROCEDURE TO
CLEAR PROGRAM main

* main.prg is external so that it can simply be replaced on a live server when new code is introduced (sort of like asp.net)