[defns.access] [basic.lval] Clarify what and how can be accessed

[languagelawyer]

struct S { int i; } s;
auto u = (unsigned&)s; // accesses s, which is an object of class type

So the Notes are not accurate enough.

[jensmaurer]

[basic.lval] p11 formulates the aliasing constraints, and it uses "access". So, it would be good if "access" also applied to reads/writes made invalid by the aliasing rules.