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chaPter 8 • analyzing systems Using Data Dictionaries 211

Data Flow Diagram Data Dictionary

Data Data Data
Flow Structure Elements
Data Flow Description
Form
XXX XXX XXX

Data Data Data
Store Structure Elements
Data Store
Description
Form
XXX XXX XXX

Figure 8.1
How data dictionaries relate to data flow diagrams.

The four data dictionary categories—data flows, data structures, data elements, and data
stores—should be developed to promote understanding of the data of the system. Procedural
logic is presented in Chapter 9, entities are discussed in Chapter 13, and messages and use cases
are presented in Chapters 2 and 10.
To illustrate how data dictionary entries are created, we use an example for World’s Trend
Catalog Division. This company sells clothing and other items by mail order, using a toll-free
phone order system (or faxing the mail order form), and via the Internet, using customized Web
forms. Regardless of the origin of the order, the underlying data captured by the system are the
same for all three methods.
The World’s Trend order form shown in Figure 8.2 gives some clues about what to enter
into a data dictionary. First, you need to capture and store the name, address, and telephone num-
ber of the person placing the order. Then you need to address the details of the order: the item

Figure 8.2
An online order form from
World’s Trend Catalog Division.