The concept of "profiles" (i.e. selecting the optional elements of the level A model actually used in a service when creating a service specific sub-schema, plus optional level B extension elements) is widely used for DATEX services. The methodology supports this, but the term "DATEX profile" isn't even mentioned in the Methodology document. This is confusing, some basic explanation should be included.
Section 2.5 on profiles added for v2.1 to provide basic explanation of the concept.