Intl Extension Uses The RFC 4646 Language Tag
In the PHP intl extension, specifically the Locale class, it says:
Locales are identified using RFC 4646 language tags
RFC 4646 is deprecated
The reason I mention this is that RFC 4646 has been deprecated in favour of RFC 5646.
I had intended to use the intl extension to translate ISO 639 codes to their respective language name (e.g. en to English). Whilst this is not essential, it would be a helpful ability to have available.
ISO 639 changes frequently
The 639 language codes are actively maintained and altered by their respective registration authorities. This is not a hypothetical concern either, just see the change-log for ISO 639-3.
The use of the now deprecated language tag leaves me a little concerned about how actively the intl extension is being maintained; RFC 5656 was released in 2009, this is hardly a cutting edge standard.
Question
- Are the ISO-639 language codes used by intl updated regularly?
- Can intl be relied upon as an authoritative lookup resource for ISO 639?
- If not, is there an authoritative lookup resource for ISO 639 in PHP?