Daniel Ford wrote:
So my question now is, how does one know which file to search for zone/rules for any given region/city from zone1970.tab?
One doesn't. Traditionally, one reads all the data source files. It's a bit tricky to determine automatically which files these are; the Makefile knows which files to feed to zic, but to get it to hand over that information requires executing the Makefile with a fully-functional make(1). A recent innovation makes it easier, though: the tzdb-*.tar.lz distro includes a tzdata.zi file, which is in the source format and includes all of the data. It's not actually a source file, not including things like comments, but if you want to automatically process the data from the source format then it's a sensible starting point.
And please don't answer 'run such-and-such a program from the code area',
It's not a given that there would be an answer that avoids that sort of process. Traditionally we haven't had much concern about direct users lacking a full-strength coding environment. -zefram