set-language-environment-hook

set-language-environment-hook is a variable defined in `mule-cmds.el'.
Its value is

(url-set-mime-charset-string)

Original value was

• This variable may be risky if used as a file-local variable.

Documentation:
Normal hook run after some language environment is set.

When you set some hook function here, that effect usually should not
be inherited to another language environment. So, you had better set
another function in `exit-language-environment-hook' (which see) to
cancel the effect.

You can customize this variable.