UMLR — Concrete specialization of the Relationship meta-class are missing

Concrete specialization of the Relationship meta-class are missing. Except few cases restricted to very specific usages (import/merge, association), and according to the current meta-model, all concrete instaciations of Relationship are Dependencies. This situation has an undesirable side-effect in UML models but also in some UML profiles like SysML and MARTE. Indeed, specialized or extended relationships like Deployment or Allocation generate unexpected dependencies between related elements. A solution might be to add a concrete (Directed)Relationship meta-class in the meta-model. The concept of "Allocation" is very generic and might provides that meta-class. It would be a convenient generalization for Deployment.