UMLR — Section: 18.3.6

Figure 18.8 includes a Metamodel formalism which has never been introduced, in particular with respect to customized metamodels. The presentation as a package with a triangle is new at this point. Although the concept of a metamodel is verbally explained in the Infrastructure, there is no abstract syntax. It becomes implicitly clear that a metamodel is a package. I suggest to insert a definition of a Metamodel as a subclass of Package in the Infrastructure document or in the Profiles chapter of this document. This also allows to explain what is meant by "applying a metamodel". Also, the term "a UML2 metamodel" (p. 666) is unclear, taking into account that UML2 itself is a metamodel. This all should be clarified due to the importance of the metamodel concept in this chapter. The same applies to the respective chapter of the Infrastructure document.