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

[Paul Eggert]

On 3/5/19 3:07 PM, Guy Harris wrote:
> Is there any information about whether "UTC" or "UCT" is the more commonly used abbreviation in documents in English?

"UTC" is far more common. For example, for me Google reports about 4,220
hits for the query "Universal Coordinated Time (UCT)" and about
1,080,000 hits for "Coordinated Universal Time (UTC)". For Google
Scholar the numbers are 210 and 11,800 respectively. For Google Books
they are 493 and 12,500 respectively. In all cases the double-quote
characters were in the query.

My vague impression is that "UCT" was formerly more popular than it is
now, but it's never been as popular as "UTC".