Mark Horton says:

In my implementation, I added two fields to struct tm, for the hours and minutes in the time zone which resolved the ambiguity. (both are negative for us in the USA)

kre says:

Secondly, I'm not sure why you chose to have West of Greenwich being negative. All previous uses of timezone offsets in Unix have been the other way - West of Greenwich positive.

I favor the ISO rule. Every international organization (but, I'm sure there are exceptions) has adopted the East of Longitude 0 is positive; west is negative. If we are proposing POSIX as an international standard, we should accept the international rules. The UNIX convention is unfortunately wrong. It was one of those 50/50 chances (like determining whether the flow of electicity is positive or negative) that was incorrectly chosen. Dems da breaks. Bob Devine