Welcome

It has been 10 years since this introduction was last updated and while there have been lots of changes in the way things happen in the meantime, the original problems that prompted me to set up this particular site still have not been addressed. Now that I have retired from full time 'employment' I can spend more time on these more interesting projects and hopefully make some more useful contributions. I put 'employment' in quotes simply because having been self employed in my own business for 45+ years, just how I spent my time in the past was my own decision and THAT perhaps was not the best use of the time available. However that is another discussion for a different forum.

Many people who are using a timezone setting will probably not know that when looking back before the adoption of UTC in 1972, much of the history is not currently supported. IANA is the current home of the tz database following a recent problem with legal action against the original team, and most systems synchronise their data against this reference. The main problem with this source is that while there is some historic material contained in the data, and changes to a locations history from a nominal set of rules is not currently supported. There is currently no great acceptance that returning correct historic data is something that the tz database should do, and even what probably incorrect data was included is currently being removed! So this is an initial attempt at providing a home for pre-1972 material and a fully documented historic tz database. That has not changed since it was originally written 10 years ago and so I need to allocate time to make some real progress.

As a base for this we have a couple of  publicly accessible sources of location information, both of which provide a link to a post-1972 timezone identifier. So all that is required is to enhance that material with the correct pre-1972 material. Obviously for much of the world, the historic evidence may be difficult to access, having been lost over time, but a base for every location will be it's Local Mean Time (LMT) when one goes back far enough. It is the move from time determined by the sun, to a common clock controlled time for an area which may be more difficult to document, and even today there is contention between 'official' time and local variations to that.

What we need to establish initially is a way of documenting what information is currently available, and to that end we need local historians to provide material to allow both historic variations and standards as well as the ongoing local variations to the official settings. Back in 2016 a mechanism was documented to provide a network based service to provide tz data and RFC7808 is the result. I participated in the drafting of this standard, or more accurately kept poking at the failings in the system as it stood at that time. I need to get back into just where this service currently stands and if there are actually any reliable implementations working currently. The one thing that was built into the standard is that any supplied data SHOULD identify the date from which that information is valid, and in my own case, I expect that the Isle of Man tz data should be tagged as only being valid for the last 50 or so years. That we have data in the backzone prior to that which is not normally included in packaged distributions was the main problem I was fighting at the end of the 1990's. Pretending that the whole of the UK had daylight saving changes at identical times makes historic material unreliable. Now is the time to get back into this and perhaps provide a tzdist service that DOES have the right information.

What we need todo

Local Reference Material

Links Page from tz

Other time links

Do we need Timezones - Another debate that is once again gaining traction on the tz list as once again there is pressure to eliminate DST to simplify things. But it misses the point that even a simple time offset needs to be managed and it is that which is equally problematic even without the added complexity of daylight saving switches.