An Attribute is defined in System Architect as the instantiation of a Data Element in a specific entity. An Attribute is tightly coupled to its Data Element. Therefore, a change to the value of the Datatype, Type Qualifier, default value, or Data Domain of either the Attribute or the Data Element changes that value in all attributes coupled to that Data Element.
Note When a Data Element definition name is changed, the name of the Attribute with which it is coupled also changes. This is because an Attribute is an instance of a Data Element, so when the Data Element name changes, the Attribute name also changes. Deleting a Data Element deletes all attributes which instantiate it.
Only the following values of the Attribute are modifiable without affecting the Data Element. These characteristics apply only to the instance of the data within a specific Entity:
▪Key Status: Is this instance of the data component?
▪Nullity: Can the column contain a null value in the database?
▪Uniqueness: Is the Attribute unique?
▪Column Name (defaults to the name of the Data Element)
▪Database Comments or text Description
Attributes correspond to columns in the Physical Data Model.
