This is a generic issue in many standards. For some "three months", see below is "historical". For others, the past year is contemporary. Working in Open-edi standardization (JTC1/SC32/WG1), security services(JTC1/SC27) as well as the area of geomatics (ISO TC 211) from an e-commerce, e-business, e-gov't, etc. standardization perspective, I would welcome input, ideas, etc. on some common agreement as to what we mean by "contemporary", "historical", "archival", etc.. Being involved in logistics, I not only have to know and record the local time/date to UTC (or vice-versa), I also have to be able to support "records retention" requirements of the jurisdictions in which I do business. Working in a complete electronic/digital mode, I keep records of completed business transactions only as long as I am legally required too, (e.g. via an automated time zone driven deletion routines). Can we, should combine our needs, efforts here into a new standard? Gwillim is absolutely right when he says that this is too much work for any one person (no matter how expert). looking forward to feedback, ideas - Jake Knoppers (Canada)
-----Original Message----- From: Gwillim Law [mailto:gwil@mindspring.com] Sent: January 29, 2001 1:20 PM To: tz (E-mail); alois@astro.ch Subject: Re: quality of historical zone information
Alois Treindl wrote:
Defining more zones will not be enough. it must be possible to associate every populated place with the right zone.
That's a requirement for my work, too. I have been working in the field of logistics. To track shipments, I need to be able to convert from local time to UTC, based on location. That means I have to know the historical sequence of UTC offsets for each possible location. The difference between my application and astrology is that I'm concerned with a much narrower range of dates: typically from today minus three months to today plus three months, although for archival purposes I may want to look back several years.
If the membership of the tz list, or any other group, wants to undertake to create and maintain a more complete tz archive that would do justice to the geographical aspect, I have a few principles to suggest.
Too much work is involved to expect any one person, especially a volunteer, to do it all. There's a natural way to subdivide it: by countries. In general, time zones are determined by legislation which applies throughout a jurisdiction, almost always a whole country. In many cases, a volunteer could take responsibility for several countries or a whole region. On the other hand, a country with a very complex time zone history, such as the United States, might be divided up among several volunteers. Ideally, each volunteer would be acquainted with the languages and culture of the region he or she is responsible for. Uniform guidelines should be drawn up, covering things like database design, data authentication, and update notification.
Database design: The current tz archive has an implicit database design, which is implemented in various Posix-compliant systems. This existing design is inadequate for some purposes. For example, Brazil is divided into areas that observe four different standard times. The information about which state is in each area is hidden in the comments. If a new database design allows the geographical component to be represented, Posix systems should be supported as a legacy. This might be done by taking a slice or subset of the data. Other systems might choose to take a different slice, in order to tailor the data to their specific requirements and save on storage. A logistics application might select only post-1996 data, having no need to refer further back than that.
Data authentication: the data in the existing tz archive were acquired from several sources. They're cited in the comments. They include Shanks, Whitman, IATA, and personal communications from a number of Time Zone Caballeros. None of these are really primary sources. Primary sources include laws, acts, and decrees reported in the Congressional Record, Hansard, etc., and newspaper reports of actual time zone implementation. We do have some primary sources, but they don't cover the whole world. When several sources disagree (and we don't have a primary source), someone like Paul Eggert decides which is the most reliable, and explain his decision in the comments. As new sources become available, some of the old decisions may have to be reconsidered. What we need is a file containing every available document that has clues to historical time zone data. This file could be partitioned by country or region, so that each time zone volunteer saves only those documents pertaining to his or her specific area. Guidelines should cover criteria for selecting the most reliable information from a set of documents, as well as the maintenance, back-up, and public availability of the source material.
Update notification: Some updates to the expanded tz archive would be to correct old errors. Others would be to extend time zone rules further into the future. Currently, all updates to the tz archive affect all users, and are reported to the tz mailing list. Would this still be sufficient? It would be a great help to maintain a Web site that displays all the tz archive data in a format easily understood by casual users. For one thing, more people would be able to find mistakes in the data and send in corrections. Perhaps Web pages could be automatically generated by applying a transformation to the archive.
The work I've described above would be a valuable service to the Internet community. Is there some way to finance it? For example, could certain beneficiaries be persuaded to subsidize it? Could advertising be sold on the Web site? If so, the volunteers could be paid, and the archive could be more effectively improved.
Yours, Gwillim Law