On 02/19/2018 06:55 PM, Lu, Can via tz wrote:
SGT is very commonly used in Singapore and it’s also a standard abbreviation for Singapore time. Please refer to: https://en.wikipedia.org/wiki/List_of_time_zone_abbreviations and https://en.wikipedia.org/wiki/List_of_time_zone_abbreviations
Those two sources are not reliable for real-world use, as they're derived from old versions of the tz database itself. If SGT is commonly used independtly of tzdata (in the main newspapers of Singapore, government sources and the like), that would be good evidence for its inclusion in tzdata. My impression, though, is that it's not that common in practice; though I found some occurrences in Singaporean sources, it wasn't all that common, perhaps in part because SGT also stands for "Sergeant", a use far more common than the time-zone use.