EXPRESS_ — Generic_entity usage in Abstract entity not supported

According to ISO 10303-11:2004 a GENERIC_ENTITY may be used to represent
an explicit or derived attribute within an ABSTRACT ENTITY. According to
the Meta-model the use of the syntactic element type_label is restricted
to parameters. This conflicts with ISO specification and should be
changed.

Agreed. This addition to the 2004 version of EXPRESS was overlooked in the RFC specification, and it includes AGGREGATE as well. This has several consequences for the metamodel.
The GenericElement concept is used in defining EntityTypes outside of Algorithms, and thus should be supported by the Core Package. And the same is true of the ActualTypeConstraint, according to ISO 10303-11:2004. Parts of clause 10.4 and all of clause 10.5 will therefore be moved into the Core package (clause 8).
A new abstract class will be created (ElementSource) to be a purpose-built supertype of Parameter and Attribute that relates to GenericElements and ActualTypeConstraints.
GenericElement has two possible choices of namespace - EntityType or Algorithm - with the consequence that it is of no modeled subtype of NamedType. It will simply be a subtype of NamedType with two choices of Scope.
Because the revised text moves a section of the metamodel into the Core package, it also incorporates the resolution of Issues 14068, 14070, and 13687, which affect the moved text. In particular, Issue 14070 renames GenericElement, ActualDataType, ActualStructure to ParametricElement, ParametricType, ParametricStructure, respectively. In effect, this whole section of the model has been rewritten, and the change of names makes it easier for implementors to find all the affected code.