For commands and utilities, use EXIT STATUS rather than RETURN VALUES as
appropriate (and documented in mdoc(7)).

Add 'RETURN VALUE' section header.

On memory allocation failure, return 3 as per POSIX. (from OpenBSD)

Fix .Nm usage.

Winning Strategies has placed this code into the Public Domain

convert to new RCS id conventions.

Fix spelling error in Copyright notice

Fix spelling errors.

Document the new, less restrictive, behavior of the matching operator.

Document the fact that expr is POSIX.2 compliant.

Document that string comparisons are done using the locale specific
collation sequence.

Makefile

Add a manual page.