Identifier expression syntax

1 %unqualified_id
1 %qualified_id

unqualified_id:

1 identifier
1 operator_function_id
1 conversion_function_id
1 ~ class_name
1 template_id

qualified_id:

1 ::
1.1 identifier
1.1 operator_function_id
1.1 template_id
1? ::
1.1+ 
1.1? class_or_namespace ::
1.1.1? template
1.1.2 class_or_namespace ::
1.1.3? template
1.1.4 unqualified_id