c++ grammar has no reflection of iso646.h

[nickhuang99]

In preprocessing-op-or-punc, and, and_eq, bitand... are defined as keywords. However, logical-and-expression doesn't reflect this keyword and. Neither are other keywords. This grammar is actually inherited from C programming specifiction. Particularly in header <iso646.h>, these are "Alternative Spellings". I wonder if C++ grammar should specifically add a rule about this, or do we expect C++ grammar to be built upon C-grammar?