Association and aggregation -- semantic mismatch

At the code level, a pointer (reference in Java and C#) is used to represent both association and aggregation. There is a semantic mismatch between the code and the object model .

http://www.agiledeveloper.com/articles/cloning072002.htm

Boolean: a type of Enum

the Boolean data type ... is an enumerated type, that can have one of only two values : True or False.

http://www.delphibasics.co.uk/Article.asp?Name=Logic