This chapter is a tutorial on the use of entity modelling notation to model types of entities and their parts.

In the sections which follow we describe notations for describing the properties of entities and their composition relationships including cardinality and optionality (the crows foot and dashing of lines), exclusion (the exclusion arc), recursion (looping structures), abstraction (nested boxes), the absolute (diagram root). Almost all this notation applies equally to more general types of relationship but the approach is to introduce the notation in this more restricted setting. The notation is as used in the SSADM method as described, for example, in Richard Barker's book, but with further development including the special treatment of composition relationships, and thereby their foregrounding, and the notation for the absolute.