* expression.h (enum exp_opcode): Document a register name for

	* expression.h (enum exp_opcode): Document a register name for
	OP_REGISTER.
	* parse.c (write_dollar_variable): Write the register name for
	OP_REGISTER.
	(operator_length_standard): Expect the register name following
	OP_REGISTER.
	* ada-lang.c (resolve_subexp): Likewise.
	* ax-gdb.c (gen_expr): Likewise.
	* eval.c (evaluate_subexp_standard): Likewise.
	* expprint.c (print_subexp_standard, dump_subexp_body_standard):
	Likewise.
	* tracepoint.c (encode_actions): Likewise.