Entity sets - containment and parent-child

[Mark Beall]

Entity sets can contain other entity sets, there can also be parent- 
child relations between entity sets. A couple questions on these  
concepts:

1) Does the parent-child relationship affect any of the operations on  
entity sets? For example, let's say I have a set A that has children B  
and C. If I get the entities in A is that just the entities in A or is  
it also the entities in B and C?

2) In the documentation there is an example of the entity set  
operations, but it doesn't describe some cases that seem to be  
ambiguous. For example:
- Entity set A contains abac and entity set B
- Entity set B contains abaa

What is the result of A-B? Is it c;B or just c?

Thanks,
mark