Instead of directly using `lang`, we now use `babel-lang` and `polyglossia-lang` and `context-lang`. These variables are set by the writers to the necessary values, based on the `lang` variable (which now always takes a value in BCP47 format).
Instead of directly using `lang`, we now use `babel-lang` and `polyglossia-lang` and `context-lang`. These variables are set by the writers to the necessary values, based on the `lang` variable (which now always takes a value in BCP47 format).