XMI26 — XMI spec lacks support for profiles

In principle, any metamodel can have a profile extending it.
The XMI spec only addresses producing an XMI schema for a metamodel. The XMI spec should also address the production of an XMI schema for a profile that extends one or model metamodels.

In principle, any model that is an instance of a metamodel extended by one or more profile can be augmented with the application of such profiles. The XMI spec only addresses the production of an XMI document for the model itself. The XMI document production rules should also cover the augmentation of such a model corresponding to the profile-defined stereotypes applied and to the profile-defined datatypes & classes instantiated.