Private Use Variant Subtag

Gordon P. Hemsley gphemsley at
Fri Mar 30 18:39:18 CEST 2012

Hello all,

I'm in the process of implementing some BCP 47–related parsing, and
I'm using private use subtags as a placeholder for subtags that will
be output as-is, rather than being mapped to something else. The
problem is, there do not appear to be any variant subtags set aside
for private use.

So I have a few questions:
(1) Am I allowed to just use unregistered variant subtags in the hope
that they never get registered? (I'm guessing that's frowned upon.)
(2) Would it be possible to register or set aside one or more variant
subtags as private use?
(3) If the answer to (1) and/or (2) is "no", what is the recommended
way to test always-meaningless variant subtags?


Gordon P. Hemsley
me at

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