Langauge code allow more characters to insert

[Master-Overlord]

Hey there I am setting up store with Serbian lating language and correct one is sr-Latn-RS as Serbian has 2 letters but in language code I can insert only xx-xx. 

Can you allow inserting more characters there in some future minor update?

IETF regulation regarding this;

Quote

To distinguish language variants for countries, regions, or writing systems (scripts), IETF language tags combine subtags from other standards such as ISO 639, ISO 15924, ISO 3166-1 and UN M.49. For example, the tag en stands for English; es-419 for Latin American Spanish; rm-sursilv for Romansh Sursilvan; sr-Cyrl for Serbian written in Cyrillic script and sr-Latn-RS written in Latin script; nan-Hant-TW for Min Nan Chinese using traditional Han characters, as spoken in Taiwan; yue-Hant-HK for Cantonese using traditional Han characters, as spoken in Hong Kong; and gsw-u-sd-chzh for Zürich German.

Thank you!