Yeah! We work around that in our logic at FastMail by choosing the largest population area which exactly matches the tzmapping data (generally it's from an ica

Yeah! We work around that in our logic at FastMail by choosing the largest population area which exactly matches the tzmapping data (generally it's from an icalendar file with some weird name and some rules which show the next couple of timezone transtions) It's ugly and horrible, but that's life.