| 4. as the name "Central Standard Time" in China was created by ROC,
I always assmed that "CST" in China was "China Standard Time" - but these names are largely meaningless.
IIRC, when this issue was discussed on-list a few years ago, I had asked trivia nuts in Taiwan, and was told that historically +0800 referred to Chungyuan Time. Chung Yuan is normally translated as "Central Plains". After the Pinyan orthography reforms, this is now transliterated as Zhongyuan, The "Zhong" is the same character in Zhongguo, from where we get the epithet "Middle Kingdom" for China.
https://en.wikipedia.org/wiki/Zhongyuan
-- Sanjeev Gupta +65 98551208 http://www.linkedin.com/in/ghane
True, but nowadays only people in Taiwan call their time as Chung Yuan/Zhongyuan/Central plains time despite it is referring to part of mainland China. The historical name is abandoned and unknown within mainland China. I guess it can also be interpreted as C=China, but that would violate the rule of not to use country name for timezone name, although this is not a major violation and can probably be explained by stating that the name china mean something more than the country's name
Currently the commentary for Asia/Urumqi says that it covers "Xinjiang time, used by many in western China". Some people in western China use +06, some use +08 (Asia/Shanghai in our database), and the geographical boundary between the two sets of uses is indistinct.
My understanding, from speaking to people who have stayed in the region, is that the distinction is highly ethnic and linguistic (Han/non-Han). People are aware of both time zones, and choose either +0800 or not if they are speaking Mandarin, or not. Hotel receptionists will, when speaking to foreign guests, explicitly specify timezone, as will local business contacts. There is no real geographical line here.
May I refer you to: https://en.wikipedia.org/wiki/The_City_%26_the_City ?
-- Sanjeev Gupta +65 98551208 http://www.linkedin.com/in/ghane
hum yes, the divide is ethnical, but so far all the sources i have read seems to be for only Xinjiang and none of them cover Tibet/Qinghai, i.e. no indication saying ethnic non-han in Tibet/Qinghai are also using this UTC+6. So, where is the boundary that nobody use UTC+6? If it is Xinjiang only then the commentary can be edited to better reflect the usage situation