On 2022-06-30, at 13:01, tom petch <daedulus@xxxxxxxxxxxxx> wrote: > > Second, what is a suitable constraint on a YANG string to be a language tag? If Carsten's length constraint is adequate, then I would advise authors to RYO as opposed to waiting for 6991-bis; if something more complex is needed, especially if it involves restricting the choice of characters, then it probably belongs in 6991-bis. I got the regexp from XSD [1], where Martin pointed me to. Specifically: [1]: https://www.w3.org/TR/xmlschema11-2/#language Which defines »language« using the pattern (iregexp): [a-zA-Z]{1,8}(-[a-zA-Z0-9]{1,8})* This in turn cites RFC 3066 (Obsoleted by RFC4646 [Obsoleted by RFC 5646] and RFC4647), which contains: Language-Tag = Primary-subtag *( "-" Subtag ) Primary-subtag = 1*8ALPHA Subtag = 1*8(ALPHA / DIGIT) (which is the ABNF way of saying and explaining the iregexp above.) The RFC 3066 ABNF was replaced by the more restrictive ABNF grammar in RFC 4646, which was updated a bit in RFC 5646 (demonstrating that the restrictive approach is less stable). Note that [a-zA-Z]{1,8}(-[a-zA-Z0-9]{1,8})* is a bit more than a length restriction, it is also defining the characters that can be used in a language tag. I would think that having that as a YANG data type would be good, but of course I have no opinion whether this needs to be in 6991bis. Grüße, Carsten -- last-call mailing list last-call@xxxxxxxx https://www.ietf.org/mailman/listinfo/last-call
