Each location in the database represents a national region where all clocks keeping local time have agreed since 1970. Locations are identified by continent or ocean and then by the name of the location, which is typically the largest city within the region.

then my suggestion is just to keep it simple.

The people using Beijing time, primarily Han, are doing what this definition specifies, they are setting their clocks to the largest city in their region, China clearly being the "region".

Likewise those using Xinjiang time are also doing what this definition specifies. Their "region" being Xinjiang with the largest city Urumqi.

We may want to think of regions as "not overlapping" or "not existing inside each other" but the wording of the definition doesn't require it.

So specifically, I would suggest just changing Urumqi/Asia (and likewise Kashgar/Asia) to UTC +6.

As I mentioned in my original post, I also don't think there is a need to follow PRC rules for summer time. It's use was for a few years, it is poorly documented and was not consistently followed. (The Ili bus station, for example, was still using regular Xinjiang time during the summer of 1990.) Perhaps at a later date we can figure out those crazy summers of four time standards.

-mld

On Dec 8, 2009, at 3:43 AM, Alan Barrett wrote:

Perhaps it would be easier for people to choose between the available
options if the comments said "using Xinjiang time" and "using
Beijing time". I think users are more likely to know whether or
not they want Xinjiang time than to know whether or not they want
an offset 6 hours from UTC.

--apb (Alan Barrett)