What are the characteristics of "Target for key" and "General class axioms" in the description of the class?

Question

Actually the question in the header. When should I use these properties? I tried to change them but nothing happened. Could someone explain me that?

Answer 1

Target for Key represents HasKey in OWL2.

An HasKey axiom states that each named instance of a class is uniquely identified by a (data or object) property or a set of properties - that is, if two named instances of the class coincide on values for each of key properties, then these two individuals are the same.

An example is:

RegisteredPatient HasKey: hasWaitingListN 

General class expressions represent Complex class expressions. They are not often used but you can use them to express complex statements in OWL.

For example:

HeartDisease EquivalentTo: Disease and hasLocation some Heart

Also, take a look at this great example on how to define complex class expressions.