Section 3 - what's in or out?

I know we've discussed this before, but clause 4 does feel like a bit of a grab-bag of some terms but not others. For example, "diagnostic message" and "application domain" are defined, but "type", "generics", "lambda", "class", "struct", "value type".

Clause 4 does say that other terms are defined within the standard, but at least some are in two places - for example, application domain is in clause 4 but also as bold-italic in clause 9.

It would be useful if we could have a good set of criteria to define which terms should be present.