> there's U+E0001 (LANGUAGE TAG) and U+E007 (CANCEL TAG) and you can put a language code between those, e.g. "\uE0001ja-JP\ue007". "ja-JP" part is also written

> there's U+E0001 (LANGUAGE TAG) and U+E007 (CANCEL TAG) and you can put a language code between those, e.g. "\uE0001ja-JP\ue007". "ja-JP" part is also written in tag characters, so it's actually E0001 E006A E0061 E002D E004A E0050 E007F and doesn't render even in unsupported environments.