I have a couple of questions that I hope someone can give guidance on. These are sparked by the change from IDs like "America/Catamarca" to "America/Argentina/Catamarca" In CLDR (http://unicode.org/cldr/), we are using the IDs to access different localized names for the time zones. Each time a zone ID changes, we have the choice of either updating all the localized files that use that ID, or leaving them be and using the old ID. To make our maintenance easier (and make it easier for implementations), I'm inclined to recommend that we maintain stability as of a given date; that we never change an ID after that point. 1. Would there be any downside to such a policy? 2. I was not able to find documentation as to whether there is a policy disallowing 'retired' IDs to be reused later for a different timezone. Some might think that it is so obviously a bad policy to reuse IDs that it doesn't need stating, but ISO has reused country codes, for example, causing no end of problems for stability. 3. What was the reason for the change for Argentina? Is this a one-off aberration, or can we expect America/Chicago to change to America/United States/Chicago, America/Vancouver to change to America/Canada/Vancouver, and so on down the line? 4. Are links expected to be definitional and stable? That is, if I ever have two IDs that are related by a link: Link A B Can it ever be the case in the future that the IDs A and B are "unlinked", and given different rules? Or is it that links in certain files are stable? 5. A side note: when examining the links, and assuming that they are of the form Link <new> <old> there are a small number of links that are "not final", meaning that what they link to, itself links to something else. While not formally an issue, it might be more convenient (and transparent) if these were put in a 'canonical' form. 13 America/Rosario => America/Cordoba # NOT FINAL => America/Argentina/Cordoba 39 Brazil/Acre => America/Porto_Acre # NOT FINAL => America/Rio_Branco 79 GMT+0 => Etc/GMT+0 # NOT FINAL => Etc/GMT 80 GMT-0 => Etc/GMT-0 # NOT FINAL => Etc/GMT 81 GMT0 => Etc/GMT0 # NOT FINAL => Etc/GMT 82 Greenwich => Etc/Greenwich # NOT FINAL => Etc/GMT 99 Navajo => America/Shiprock # NOT FINAL => America/Denver 137 Universal => Etc/Universal # NOT FINAL => Etc/UTC 139 Zulu => Etc/Zulu # NOT FINAL => Etc/UTC Mark