On 2/18/19 7:56 AM, Michael H Deckers via tz wrote:
this is the only case where there is a name in backzone/ that does not occur as a link in the remaining data.
Yes, that's correct. The 'backzone' file mostly holds data I created long ago that was later determined to be out of scope for tzdb, and so moved to 'backzone' with Link lines left behind for backward-compatibility reasons. Once that was done, there has been little motivation to create more 'backzone' entries, they're out of scope. The only exception so far has been Hanoi, as I later got high-quality data for Vietnam from Trần's book that was useful for improving Asia/Ho_Chi_Minh, and puzzling the data out gave an entry for Hanoi that seemed worth recording in 'backzone' even though it's out of scope. This exception doesn't need a backward-compatibility link, since there's nothing to be backward-compatible to.