This tag is intended for all questions related to name/identifier scoping in the various languages used in teaching. It can also be used for questions concerning the kind of scoping (e.g. lexical v. dynamic).
Students often have difficulty knowing where a declaration or definition of an identifier/token applies in a program. Different language use different models. Even different flavors of a language use different models (Common Lisp v Scheme). Apply this tag to such questions, both for the operational detail and for the theoretical underpinnings. Even implementation questions are welcome.
At a concrete level name visibility in general might be appropriate, say packages in Java and namespaces in several languages.