On 10/08/14 20:14, Paul Eggert wrote:
Because the tz database is so small and stable that it's feasible for one very-part-time volunteer to merge everything into a single branch that's almost always near production quality, tagged branches wouldn't bring that much to the table. It'd of course be OK if contributors wanted to take the time to make a tagged branch for each potential change, but as far as I know no tz contributor does that now and I'd rather not impose that kind of version-control bureaucracy on future contributors (including myself :-).
Modern tools allow a lot more analysis than used to be possible, and as well as the github view, there are other projects with clones of that. The next step is to provide the data with a different view, and that is one where one can simply plug in a version id and pull out data for that version. I don't think any of the current third part sources have that capability? This would make managing the historic data a little easier, but in reality that is dwarfed these days by the annual changes going forward ... Recording the tz version with a timestamp only works if one can then decode it and update it if required. My own Hg DVCS view allows me to step through the history of file changes so Ican check this manually but I'm back to the point I was at several years ago where I want the data in a relational database with a version tag, and all I need to add IS the diff's each release ... For some historic offsets we do need to indicate a level of uncertainty, which is why I was saying 'unknown' at which point the comfortable offset comes purely from it's location. That tz provides a mean offset with perhaps an hour or more window is the point here. If a location is using time based on a central clock rather than LMT then there can be a substantial change in offset. There was a discussion about the shear volume of data that could be added but recording when a particular location came into a tz entry is something that needs to be recorded outside of tz? It's only the evolution of those tz's themselves which forms part of the data? -- 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