In ISO 15926 the definition of cardinalities is exactly the opposite of the customary definition.
This topic explains why and how.
Cardinalities - customary
Let us take the relationship between a CENTRIFUGAL PUMP and IMPELLER.
Normally a Cardinality defines the minimum and maximum number of occurrences of one entity for a single occurrence of a related entity.
So a CENTRIFUGAL PUMP in general has one to many IMPELLERs, and when we specialize that to a TWO-STAGE CENTRIFUGAL PUMP it has two IMPELLERs.
In these diagrams a relation is shown.
Cardinalities - ISO 15926
In ISO 15926 relationships are understood to be classes themselves that HAVE, not ARE, relations:
Let's focus on such Relationships:
This diagram shows that myPump shall be involved in exactly two member Relationships at any point in time and myImpeller#1 may be part of myPump, the same holds for myImpeller#2.
ClassOfRelationship, and all its specializations, has an end1Cardinality and an end2Cardinality relation to dm:Cardinality.
So, here the cardinality is in fact attributed to the ClassOfRelationship and not to the related things.