The Data Item Set
Each subject area has its own subset of more detailed information. This more detailed description of the subject area can be depicted in a separate diagram called a data item set, or DIS. The DIS describes in much greater detail the characteristics of the entity that it portrays. Some of the things found in the DIS include:
- • The key, or major identifier of data for the subject area
- • Attributes about each subject area
- • Grouping of the attributes
- • Foreign keys, or relationships to other subject areas
Figure 12.2 on the next page shows a DIS.
