Reference Initialization - modelint/shlaer-mellor-metamodel GitHub Wiki

When an instance is created, each referential attribute, just like any other attribute, requires an initial value. Since this value can, and should, be determined systematically, the modeler does not supply it explicitly. Instead, the modeler provides the name of the relationship and a reference to each of the target instances.

In the simple case there will only be one target instance. In the case of an association class the same attribute may r