As long as the file isn't and mde or ade, the text depiction of the code
should still be available for accessing the same way it was when you created
the file. This will be true for Excel also, except that the file extension
is different for and Excel compiled only file. If you do make a compiled
only file, keep a copy of the original file with the text code so that you
can make changes later.
If you do an Internet search, you may find some tools to help reverse
engineer the compiled code. I have heard of some, but I don't know how good
they are.
