Martin writes:
> Okay, maybe this is a dumb question, but surely a file can only be built by
> it's creator? (literal logic at work here!)
 
True, but the :BUILD command can be used for more than building files...
 
:FILE FOO,NEW;DEV=DISK;SAVE
:PURGE *FOO                   << THIS BUILDS THE FILE FOO >>
:FILE FOO,OLD;DEL
:BUILD *FOO                   << THIS PURGES THE FILE FOO >>
 
G.