The pages on this site contain documentation for very old MS-DOS software,
purely for historical purposes.
If you're looking for up-to-date documentation, particularly for programming,
you should not rely on the information found here, as it will be woefully
out of date.
Error Message
Error 158: Unit expected
A USES clause in a program called for a file that did not
contain a UNIT heading.
A used file must begin with a heading:
UNIT <identifier>;