[loc-en-dev] grandfathered language tags

[Yoshito Umaoka]

I scanned the latest language tag registry - 
http://www.iana.org/assignments/language-subtag-registry

There is a category - grandfathered.  Use of these tags are valid in 
BCP47 language tag.  Some of them were deprecated and its preferred 
"well-formed" mappings.  Below is the full list of grandfathered tags 
currently available (File-Date: 2009-01-13).

art-lojban(deprecated) -> jbo
cel-gaulish
en-GB-oed
i-ami
i-bnn
i-default
i-enochian
i-hak(deprecated) -> zh-hakka
i-klingon(deprecated) -> tlh
i-lux(deprecated) -> lb
i-mingo
i-navajo(deprecated) -> nv
i-pwn
i-tao
i-tay
i-tsu
no-bok(deprecated) -> nb
no-nyn(deprecated) -> nn
sgn-BE-fr
sgn-BE-nl
sgn-CH-de
zh-cmn
zh-cmn-Hans
zh-cmn-Hant
zh-gan
zh-guoyu(deprecated) -> zh-cmn
zh-hakka
zh-min
zh-min-nan
zh-wuu
zh-xiang
zh-yue

I'm wondering if we should include the support for grandfathered tags, 
especially ones which do not have well-formed mappings.  If we want to 
support such cases, I would expect the whole string is handled as a 
single unit (do not try to parse them out into separated fields.). 
Anyway, I'd like to get your inputs.

Thanks,
Yoshito