Applying Likely-Subtags algorithms may add non-IANA registered subtags

[anba]

CLDR contains private use region entries for Kosovo (XK) and Outlying Oceania (QO) which are not official IANA assigned region subtags. That means for example when applying the "Add Likely Subtags" algorithm, the returned language tag may contain non-IANA registered subtags:

js> new Intl.Locale("aln").maximize().toString() 
"aln-Latn-XK"

Do we care about this case? Is it acceptable to return non-IANA registered subtags or do we need to filter them out?

[littledan]

What would be the reason for filtering them out?

[srl295]

I don't think we should filter based on IANA registration, just as string operations should not filter out non-assigned Unicode code points.

[aphillips]

Um... XK and QO are most definitely in the registry---as private use subtags. Filtering these subtags out would be wrong.

[littledan]

OK, It seems like we are all in agreement that these regions do not need to be filtered out.