From LWG3149:

• "immediate context" is used but never defined. It is used in reference to variables, expressions, and stand-alone as ``immediate context'', yet there is only a definition for "immediate function context".

This is CWG 1844.

• What is an unrelated context? E.g. LWG3149 adds this in [concept.defaultconstructible]:
  "Access checking is performed as if in a context unrelated to \tcode{T}."

This is library-speak for "metaprogramming machinery cannot access protected or private class members regardless of the context in which they are evaluated". For example, this program:

class S { 
  S() {}
  static void f() {
    S s; // Fine
    static_assert(std::default_constructible<S>); // ill-formed
  }
};

is ill-formed despite that std::default_constructible<S> is evaluated where S's default constructor is accessible.

The individual commits need "Also fixes NB ..." cross-reference to the NB comments they address, where applicable.
For example, LWG 3277 fixes US 261.