Over the years, I've developed a sizeable set of Excel function macros
to perform a variety of engineering calculations. These macros were
developed using Excel v. 4.0 macro language. I'm using MS Office X on
a Mac G3 powerbook.

As recently as a few months ago I was able to modify the source
spreadsheet/macrosheet file and create updated add-in files for the
macros. However, I've tried doing this again today and cannot save the
modifed macro sheet as a valid add-in file.

It's possible I'm missing or forgetting something...or perhaps
Microsoft has issued an update which has completely removed this
fuctionality.

Any advice on how to create Excel 4 function macros under Excel Office
X is much appreciated. There's little incentive for me to reprogram
the macros in VBA....or whatever is now used for programming function
macros these days.

Thanks for your help.