On 07/01/2014 02:13 PM, Andrew Cunningham wrote:
> On 1 July 2014 03:41, Mark K. Ehlert <[log in to unmask]
> <mailto:[log in to unmask]>> wrote:
>     Stuart Yeates <[log in to unmask]
>     <mailto:[log in to unmask]>> wrote:
>         My biggest issue (that's not covered in the doc, but which I've
>         already fed to the doc's authors) is that BIBFRAME mandates
>         three-letter language codes, where available, while core RDA
>         mandates two-letter language codes, where available.
>     To my knowledge, RDA has no such instruction.  There is RDA 7.13.2
>     (Script), where we're told to "expression the language content of
>     the resource using one or more of the terms from ISO 15924..."
>     (mentioned also under 0.12).
> although that in its self is insufficient, esp for Romanisation, where
> it isn't possible to identify which Romanisation scheme is being used.

In another message in this thread [log in to unmask] mentions BCP47 
( which does solve this problem, giving 
the example of:

"MN-cYRL-mn" [...] meaning: Mongolian written in the Cyrillic script as 
used in Mongolia.

BCP47 also has language as to when to use two letter codes and when to 
use three letter codes; allows private use tags for idioglossia / 
cryptophasia; etc.