The main problem that everybody seems to be skirting around is that the tz database has NO interest in exactly where someone is located and there is no remit TO manage that. Even tzdist which was the latest attempt to plug a major distribution hole has no remit on supplying the correct data for a particular location! Both are simply managing the set of rules that anybody can use where ever they are. Importantly allowing third parts to work out a local time for some elsewhere in the world. Some other data source is really needed to serve up the CURRENT set of rules for a location, and that is probably only currently possible using geonames.org which uses the current timezone_id and it's own simplified timeZone.txt table! What is missing is any historic (or ongoing) changes to that information, such as a location that was using one tz rule set but moved to another. In addition any pre-1970 material can not be identified. tzdist has the remit and tools to fill one of the holes that tz on it's own can not and that is historic changes TO the rule sets. My interest in the tz database came from a major problem with material that had been normalised to UTC time but there was no record as to what rules had been used TO normalise the data, so one could not verify if the CURRENT tz rules were appropriate for establishing the then local times. As Paul has quite rightly pointed out, much historic data was invented, so CORRECTING the data when more accurate information is established is perfectly correct, but one needs to be able to also establish just which rules have changed and one can then adjust the material that is now suspect ( - IF APPROPRIATE ;) ) The whole point of tzdist was to sort current day problems, so if a mobile device with a stored calendar lands in a new location where there has been an 'unscheduled' change of tz rules that change CAN be propagated quickly without needing a full tz update but that will only work if someone is actually running the primary tzdist source. Moving forward, that primary tzdist source needs to maintain a full historic record prior to 1970 since it also provides the base from which rules for historic data normalization can be managed. It allows for the tz timezone_id's to be used to identify the base rule sets, but allows new rule sets to be created ... just without any rules on just how THAT is managed :( Potentially any geonameid could have it's own individual tzdist dataset and track the history of changes as a location moves from one political jurisdiction to another and show it's simple solar time as appropriate. Something that neither tzdist or tz is actually mandated to supply? Merging geonames.org with openstreetmap.org one gets graphic displays of the area that timezones CURRENTLY cover, but one can not establish if the same offsets applied back in the 1960's when DST local times are well documented. And both databases throw away the historic data to those mappings along with a whole load of other historic material. While the vast majority of users probably could not care less, the annoyance here is that the material existed so it's not as if we are asking for extra work, just a mechanism that remembers that say in 2014 the Crimea moved from one set of tz rules to another. Once the mechanism is in place, then as new historic material comes to light, the historic record can be corrected and tzdist has the mechanism for that in relation to timezone rules. So as a start ... what has happened to tzdist. The full historic record of tz changes can provide a complete set of data that has been used over the last 20 years and as new changes are logged in now they can be pushed to tzdist while also maintaining tz distribution for off-line population systems. -- Lester Caine - G8HFL ----------------------------- Contact - http://lsces.co.uk/wiki/?page=contact L.S.Caine Electronic Services - http://lsces.co.uk EnquirySolve - http://enquirysolve.com/ Model Engineers Digital Workshop - http://medw.co.uk Rainbow Digital Media - http://rainbowdigitalmedia.co.uk