Above and beyond attributes, operations, responsibilities, and constraints, you can add still more information to a class in the form of notes attached to the class.
You'll usually add a note to an attribute or operation. Figure 3.14 shows a note referring to a government standard that tells where to find out how serial numbers are generated for objects in the WashingMachine class.
Figure 3.14 An attached note provides further information about the class.
Bear in mind that a note can contain a graphic as well as text.