IDL43 — Some standardized annotations use keywords as identifiers

8.3.3.1 "@default" and 8.3.6.2 "@oneway" specify standardized annotations that a user is not allowed to make use of because grammar rule 225 (in 7.4.15.4.2) states that a <scoped_name> is used to identify the applied annotation. From rule 4, a <scoped_name> is built out of <identifiers> which can't be keywords (see 7.2.1, 7.2.3, 7.2.4).