An Information Model Is a Template for Data

An information model is an object model stored in the Repository. An information model accommodates the kinds of things that your software tool manipulates and thus includes classes, relationship types, and properties.

A class is a template to which stored objects must conform. For example, the book class is a template; when you store an object representing a book, it can have a title and a number of pages, but it cannot have a birthday.

A relationship type is a template to which stored relationships must conform. For example, the "publication" relationship type is a template. When you store a relationship to indicate the publication of a book, the relationship you store must conform to the "publication" relationship type.

A property is a template to which stored property values must conform. For example, when you store a birthday, you must store a date. You cannot store "Abcdefg".

The typical object model stores objects that fall into three classes:

• The Property class — Each instance of this class describes a property. For example, one instance of this class describes the Birthday property.
  
  
• The Relationship Type class — Each instance of this class describes a relationship type. For example, one instance of this class describes the Authorship relationship type.
  
  
• The Class class — Each instance of this class describes a class. For example, one instance of this class describes the Publisher class.