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212 Part 3 • the analysis Process

description, size, color, price, quantity, and so on. The customer’s method of payment must also
be determined. Once you have done this, these data may be stored for future use. This example is
used throughout this chapter to illustrate each part of the data dictionary.

Defining the Data Flows
Data flows are usually the first components to be defined. A systems analyst determines system
inputs and outputs by interviewing, observing users, and analyzing documents and other exist-
ing systems. The information captured for each data flow may be summarized using a form that
contains the following information:

1. An optional identification number. Sometimes the ID is coded using a scheme to identify
the system and the application in the system.
2. A unique descriptive name for the data flow. This name is the text that should appear on the
diagram and be referenced in all descriptions using the data flow.
3. A general description of the data flow.
4. The source of the data flow. The source could be an external entity, a process, or a data
flow coming from a data store.
5. The destination of the data flow (same items listed under the source).
6. An indication of whether the data flow is a record entering or leaving a file or a record
containing a report, form, or screen. If the data flow contains data that are used between
processes, it is designated as internal.
7. The name of the data structure describing the elements found in this data flow. For a simple
data flow, it could be one or several elements.
8. The volume per unit of time. The data could be records per day or any other unit of time.
9. An area for further comments and notations about the data flow.
Once again, we can use our World’s Trend Catalog Division example from Chapter 7 to illustrate
a completed form. Figure 8.3 is an example of the data flow description representing the screen
used to add a new CUSTOMER ORDER and to update the customer and item files. Notice that

Figure 8.3
An example of a data flow
description from World’s Trend
Catalog Division.
Data Flow Description
ID
Name Customer Order
Description Contains customer order information and is used to update the

customer master and item files and to produce an order record.
Source
Customer Destination
Type of Data Flow Process 1
File
Screen
Report
Form
Internal
Data Structure Traveling with the Flow
Order Information
Volume/Time
10/hour
Comments Order record information for one customer order. The order
the order-processing department directly.
may be received by Web entry, email, FAX, or by the customer telephoning