timezone magic number

Arthur David Olson ado
Fri May 5 17:35:41 UTC 1995

> > I have one comment regarding the timezone file format.
> > 
> > Why not use a few of 20 remaining bytes in tzh_reserved field for a
> > magic number that would be unique to timezone data files?  4 bytes at
> > the beginning of the file would be great, but if you're concerned
> > about space then 2 bytes would do the job if selected carefully.
> I would like to add that we need it to be PERSISTENT: even if timezone
> would not exist anymore its magic number should be preserved. It
> makes possible to use them for database storage.

I'm unclear here.  One possibility would be to drop a string such as
			try man tzfile
(or something shorter) into each timezone file at a fixed place, so that
the UNIX "file" command (in conjunction with an appropriate "magic" entry)
could identify it.  (A string such as that above might have the benefit
of making the file self-documenting.)  But the suggestion above seems to
involve generating particular tags for particular files.

Can anyone make things clearer?


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