The warning message for $D is:

ignoring BP directive `{$d-}' which is unnecessary in GPC

CW Pascal uses $D to turn symbol generation on and off (typically used to disable around sensitive areas of code like password / serial number / authentication / etc).

I don't know if there is any equivalent for the Mac directive, but the warning is a bit inaccurate for Mac. Perhaps it should just be the normal "unknown directive", or perhaps there should be a general scheme for setting ignored directives (which could include $D for BP, and could include $unused for Mac).

Or perhaps the warning message should just be changed a little?

Enjoy, Peter.