Association name: must have a name or roles or both
Role: must have a name or roles or both
The notation for a binary association is a line or path connecting the participating classes.
The association name is placed along the line with the rolename and multiplicity at each end, as shown in Figure 2-7.1
An association can also have attributes of its own, in which case it is both an association
and a class, an association class
(see Figure 2-7.2).