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230 Part 3 • the analysis Process

repository can also contain information about project requirements and final system deliverables; and about
project management information.
Each entry in a data dictionary contains the item name, an English description, aliases, related data
elements, the range, the length, encoding, and necessary editing information. A data dictionary is useful in
all phases of analysis, design, and ultimately documentation because it is the authoritative source on how
a data element is used and defined by users in the system. Many large systems feature computerized data
dictionaries that cross-reference all programs in the database using a particular data element. The data dic-
tionary can also be used to create XML that enables businesses with different systems, software, or database
management systems to exchange data.

Keywords and Phrases

base element packed decimal
binary format physical data structure
data dictionary repeating group
data element repeating item
data structure repository
derived element schema
document type definition (DTD) structural record
Extensible Markup Language (XML) system deliverables
ID varchar
IDREF zoned decimal

Review Questions

1. Define the term data dictionary. Define metadata.
2. What are four reasons for compiling a complete data dictionary?
3. What information is contained in the data repository?
4. What is a structural record?
5. List the eight specific categories that each entry in the data dictionary should contain. Briefly give the
definition of each category.
6. What are the basic differences among data dictionary entries prepared for data stores, data structures,
and data elements?
7. Why are structural records used?
8. What is the difference between logical and physical data structures?
9. Describe the difference between base and derived elements.
10. How do the data dictionary entries relate to levels in a set of data flow diagrams?
11. List the four steps to take in compiling a data dictionary.
12. Why shouldn’t compiling the data dictionary be viewed as an end in itself?
13. What are the main benefits of using a data dictionary?
14. What does Extensible Markup Language (XML) describe?
15. What is a document type definition?
16. How does a document type definition help to ensure that an XML document contains all necessary
elements?
17. When should attributes be used in an XML document?
18. What does an ID attribute ensure?
19. What does an IDREF attribute validate?

Problems

1. Based on Figure 7.EX1 in Chapter 7, Joe, one of your systems analysis team members, made the fol-
lowing entry for the data dictionary used by Marilyn’s Tours:
DATA ELEMENT = TOURIST* * * * PAYMENT
ALIAS = TOURIST PAY
CHARACTERS = 12–24
RANGE = $5.00–$1,000
VARIABLES = $5.00, $10.00, $15.00 up to $1,000, and anything in between in dollars and cents.