Inheritances (CDM/LDM)

An inheritance allows you to define an entity as a special case of a more general entity. The general, or supertype (or parent) entity contains all of the common characteristics, and the subtype (or child) entity contains only the particular characteristics.

In the example below, the Account entity represents all the bank accounts in the information system. There are two subtypes: checking accounts and savings accounts.

The inheritance symbol displays the inheritance status:

IDEF1X	E/R and Merise	Description
		Standard
—		Mutually exclusive inheritance
		Complete inheritance
—		Mutually exclusive and complete inheritance

Note:

There is no separate inheritance object in the Barker notation (see Supported CDM/LDM Notations), as inheritances are represented by placing one entity symbol on top of another. Barker inheritances are always complete and mutually exclusive, and the supertype lists its subtypes on the Subtypes tab (see Entity Properties). Only leaf subtypes can be generated as PDM tables, and the Generate option is disabled on Barker supertype property sheets.

Creating an Inheritance
You can create an inheritance from the Toolbox, Browser, or Model menu.
Inheritance Properties
To view or edit an inheritance's properties, double-click its diagram symbol or Browser or list entry. The property sheet tabs and fields listed here are those available by default, before any customization of the interface by you or an administrator.
Making Inheritance Links Mutually Exclusive
When an inheritance link is mutually exclusive, one occurrence of the parent entity cannot be matched to more than one child entity. This information is for documentation only and has no impact in generating the PDM.

Parent topic: Conceptual and Logical Diagrams