Bengali Locale Specific Data (RFC 3066)

Hi all,
It is not uncommon to observe that many (Bengalee) people in India talk in Bengali as spoken in Bangladesh. The value to add such locale specific data may be thought of as bn-BD (a two letter language code followed by optional subcodes meant for say, country)   or  as  ben-BD ( a three letter language code followed by optional subcodes meant for say, country). RFC 3066 may address this.
Such information might help in determining the locale of a user.
Thanks & Regards,
Goutam Kumar Saha