"Mark Davis" <mark.davis@jtcsv.com> writes:
1. What are the all valid Olson TZIDs 2. How to determine which are 'canonical' and which are simply included for compatibility ... 5. An explicit description of the data representation for all of the data files.
We've covered these issues in our emails so far, I think, so all you'd need to do is write it all down.
3. What is the meaning of an TZID
Sorry, I don't know what you mean by "meaning of a TZID". A TZID is just a name. But perhaps you can just consult the Theory file to see the naming convention.
4. What is the versioning scheme,
You can get many (most?) old versions at <ftp://munnari.oz.au/pub/oldtz/>; the versioning scheme should be fairly evident though I suppose it wouldn't hurt to write it up.
including assurance that:
I'm afraid there is no warranty of any kind. This is entirely an informal volunteer effort.
- once a version is issued it is never changed.
That's been true in practice. For example, once tzdata2003d.tar.gz was issued, it wasn't changed; instead a newer version tzdata2003e.tar.gz was issued.
- TZIDs are stable, in the sense that they will never be withdrawn or reused with a substantially different semantic in later versions
That's also been true in practice, mostly. Generally speaking, TZIDs are never withdrawn; they're just moved to the 'backward' file. However, I can think of one exception. In 1994 some of the GMT-related TZIDs did change their semantics to conform to POSIX. For example, the old TZID "GMT-12" was withdrawn and its replacement is called "Etc/GMT+12"; this because POSIX required a different semantics for TZ="GMT-12". This sort of confusion is one of the reasons why I don't encourage the use of TZIDs like "Etc/GMT+12".