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The current strftime code is supposed to deliver up ISO 8601 week numbers when "%V" is used

I assume that this is for a new or draft standard...

If the full name is any indication, it dates from 1988.

Is a copy available online?

The situation is akin to that of the C standard; it's copyrighted by the issuing body. A summary is available; I've put a (recompressed) copy of it in the ~ftp/pub directory on elsie.nci.nih.gov (165.112.73.1); see ftp://elsie.nci.nih.gov/pub/iso8601.ps.gz

OK, then I think I see the problem. Solaris 2.5.1 and the GNU C library both use XPG4_1994_04_09 behavior; but tz's strftime.c does not emulate this behavior correctly. (I'm guessing a bit, because I do not have the XPG4 spec.)

The following patch fixes tz with XPG4_1994_04_09 so that it emulates the Solaris / GNU behavior precisely; I've tested it on all dates from 1901-12-14 through 2038-01-18.

It's dicey as to what the right thing to do is. As long as we're deliberately making an error, we might as well err in the same way as other major implementers. Paul's suggested patch is incorporated into ftp://elsie.nci.nih.gov/pub/tzcode96i.tar.gz --ado