Standard placements of OCL Expressions
This section defines the standard places where OCL expressions may
occur, and defines for each case the value for the contextual classifier.
Note that this list of places is not exhausting, and can be enhanced.
How to extend the use of OCL at other places
At many places in the UML where an Expression is used, one can write this
expression in OCL. To define the use of OCL at such a place, the main task
is to define what the contextual classifier is. When that is given, the
OCL expression is fully defined. This section defines a number of often
used placements of OCL expressions.