Ok, so the key quote here: "If the colon is omitted each of the above TZ formats will be tried." So even if someone finds this sentence somehow this is still u

Ok, so the key quote here: "If the colon is omitted each of the above TZ formats will be tried." So even if someone finds this sentence somehow this is still underspecified. The full logic seems to be for a TZ that doesn't start with ':' : 1. First format tried, if it fails... 2. ...interpret TZ as filespec, if it fails... 3. ...interpret TZ as std with offset 0. Note that there is fallback parsing of TZ that is not described at all (essentially 3rd and 4th formats), and two fallbacks, not one.