[tz] Why is `Etc/UCT` not an alias of `Etc/UTC`?

Steve Allen sla at ucolick.org
Tue Mar 5 21:04:27 UTC 2019

On Tue 2019-03-05T15:44:27-0500 Donald MacQueen hath writ:
> Timeanddate.com says that UTC was a compromise between English and French
> speakers.

> https://www.timeanddate.com/time/utc-abbreviation.html

There is no contemporary evidence to support this myth.

By the 1950s various radio broadcast time signals were using different
expressions to correct the raw time observations to a more uniform and
smooth time scale.  In a pattern repeated over decades of history, any
differences of broadcast time signals were deemed intolerable and
demanded immediate changes even if the mechanisms for those changes
were not specified and not tested in actual use.

At Dublin in 1955 the IAU decreed that everyone should use the same
expressions and that all broadcasts should be the seasonally smoothed
version.  In publications of the time service bureaus the three
versions of UT acquired the names
English UT0, UT1, UT2
French  TU0, TU1, TU2
both sets used with and without embedded full stop (.) characters.

Every indication from the literature over time is that the three
variations of Universal Time which were decided at IAU 1955 evolved
along the same pattern to become TUC and UTC.  (The person who first
used "TUC" in print later explicitly disavowed having invented that
notation.)  Then in the 1970s came the era when various agencies
recommended use of a single abbreviation without embedded periods.

Steve Allen                    <sla at ucolick.org>              WGS-84 (GPS)
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