[gram.key] Is it in a C++98 state, or is it intentional?

[[gram.key]](https://eel.is/c++draft/gram.key) says that some declarations introduce context-dependent keywords.

1. How does a `typedef` declaration introduce context-dependent keywords, and what are they?
2. Also, does a using-declaration not introduce keywords, but `typedef` does?
3. Last but not least, are concepts missing from this section?