Private use variant subtags considered useless

[John Cowan]

Addison Phillips [wM] scripsit:

> There is a difference between a private-use variant and a private
> use subtag: you know what role a variant fills in the tag. There
> is actually text in the language, script, and region subtags about
> preferring the private use codes in the underlying ISO standards over
> using extensions for exactly this purpose. Consider:
> 
> en-QM vs. en-x-myRegion
> 
> Processors can assign "QM" to the region field, whereas "myRegion"
> is an opaque code. That's why there are two mechanisms.

Formally, that's quite true.  But whereas language, script, and region
subtags have fairly straightforward semantics, such that it's worth
knowing that Qaaa is the script even if you have no idea what the script
is, variant subtags are another matter.  All they tell you (if you can't
understand them, which will be the typical case) is that the language,
the script, the region, or something as yet unthought-of has some kind
of variant semantics.

What's worse, you don't even know which subtag the variance pertains to.
For example, he-hebr-il-yemeni, he-hebr-il-rashi, and he-hebr-il-telaviv
are all plausible registered variants and they are all formally identical.
The only thing you can do, if you don't have local knowledge, is to look
them up in the IANA registry.

But with a variant tag of xfoo, you can't even do *that* -- so in effect
you either understand it using local knowledge, or you can't understand
it at all.  In either case, you are no worse off with x-foo.

-- 
"Well, I'm back."  --Sam        John Cowan <jcowan at reutershealth.com>