Testing ExistsClass

[BentleyJOakes]

In the Families to Person test model, there is:
The Temp Family:
Mother - Zero
Mother - Two

The Oakes Family:
Mother - Mrs.Bentley

There is a rule Mother2Woman:
AnyParent <-mothers-> ExistsFamily
which produces a Woman element

Note that the Family element is an Exists element.

When this rule is executed, all three Woman elements are created.

What is the semantics of the Exists element in this case? It seems to be identical to the Any element. My understanding is that the Exists element would match on exactly one element in the entire input model. Obviously, this element is binding to both families, and also to the same family for the family with two mothers.