Ohta-san writes:
- The single letter "X" for private extensions
- The four-letter string "IANA" for IANA registered extensions
I bet my 0.001 Yen that, in the future version of ISO 639, language names
"X" or "IANA" will be registered.
The Content-Language: specification should only allow use of the
_existing_ ISO codes, for which the exact syntax, 2 ALPHA, is
known. When ISO finally is able to adopt a standard for a new
and better system for language codes, the Content-Language:
specification should be revised. If ISO happens to choose a
coding system which uses name space already occupied by IANA
registrations, something which I believe is quite improbable, we
will have to include the new codes as Content-Language: values
not verbatim, but using some transformation guaranteeing
uniqueness, such as an "i-" prefix.
/Olle