http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2010/n3092.pdf - 3.10
— An lvalue (so called, historically, because lvalues could appear on the left-hand side of an assignment expression) designates a function or an object. [ Example: If E is an expression of pointer type, then *E is an lvalue expression referring to the object or function to which E points. As another example, the result of calling a function whose return type is an lvalue reference is an lvalue. —end example ]
— An xvalue (an “eXpiring” value) also refers to an object, usually near the end of its lifetime (so that its resources may be moved, for example). An xvalue is the result of certain kinds of expressions involving rvalue references (8.3.2). [ Example: The result of calling a function whose return type is an rvalue reference is an xvalue. —end example ]
— A glvalue (“generalized” lvalue) is an lvalue or an xvalue.
— An rvalue (so called, historically, because rvalues could appear on the right-hand side of an assi