*Paul Eggert* eggert at cs.ucla.edu <mailto:tz%40iana.org?Subject=Re:%20Re%3A%20%5Btz%5D%20%5BPATCH%202/3%5D%20Replace%20some%20zones%20with%20links%20when%20that%0A%20doesn%27t%20lose%20non-LMT%20info.&In-Reply-To=%3C522616ED.6060902%40cs.ucla.edu%3E> /Tue Sep 3 17:05:49 UTC 2013/ Lester Caine wrote: >/can we at least agree that the quality of the material is heading in the right direction? / Yes, that's the idea. While I personally have no problem with tidy-up of obviously wrong data and also agree that correction of mistakes is more important than stability (which has never been absolutely pretended), I think end-users of tzdb should get a better opportunity to estimate how reliable the data are and how much trust they can put in their time zone calculations. Offsets in LMT-lines can easily be qualified as UNKNOWN. For the proposed date of 1970 as general separation point between UNSAFE and (apparently) RELIABLE I am not so sure. Would it not be helpful for end-users if there is an additional year-type attribute per zone which tells the users since when the data can be confirmed with high probability of correctness? Would require about 400+ attributes (ok, 1970 as default). I am sure for example in UK or in Germany the data are correct even a pretty while before 1970. Flexibility would be a good thing, isn't it? External APIs could support the users with this extra quality information per offset and make them better aware that historical tz data are not set in stone. Just giving a thought...