<<On Mon, 20 May 2013 14:26:10 -0400, random832@fastmail.us said:
However, the last time the use of an "X" code was proposed on this list (XJ for the disputed portion of Jerusalem, or rather to simply be able to include Jerusalem in zone.tab without making any judgement on what territory it is in), it was suggested that we should avoid using user-defined codes because some program could hypothetically consume the zone.tab file while ignoring the included iso3166.tab file in favor of its own list of country codes. I don't believe this objection was substantiated, though.
FreeBSD does this (and always has); you can look at it if you want. In general we consider the ISO 3166 Maintenance Agency to be the only source of contents for that file. -GAWollman