Creating a Constraint

You create a constraint on the Constraints tab of an element property sheet.

The Constraints tab contains the following tools:

Tool	Description
	Add Key Constraint - The element value must be a key within the specified scope. The scope of a key is the containing element in an instance document. A key must be unique, not null, and always present.
	Add Unique Constraint - The element value must be unique or null within the specified scope.
	Add KeyRef Constraint - The element value corresponds to those of the specified key or unique constraint

For general information about creating objects, see Core Features Guide > Modeling with PowerDesigner > Objects.