From Open Watcom
I would suggest a note about statements having to start in column 1 on each line. Like:
macro = text # works macro2 = text2 # warning
If not they are assumed to be part of a command list for a (possibly non-existing) target. I believe that this is a result of the ability to accept non-TAB intro for command lists.
The given warning is quite hard to understand when unfamiliar with make/wmake.