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216 Part 3 • the analysis Process

Figure 8.6
An element description form
example from World’s Trend
Catalog Division.

ID Element Description Form
Name
Customer Number
Alias Client Number
Alias Receivable Account Number
Description Uniquely identifies a customer who has made any business
transaction within the last five years.

Length 6 Element Characteristics
Input Format 9 (6) Dec. Pt.
Output Format 9 (6) Alphabetic
Default Value
Alphanumeric
Date
Continuous or
Discrete
Numeric
Base or
Derived
Validation Criteria
Continuous
Discrete
Upper
Limit <999999 Value Meaning
Lower
Limit >0

Comments The customer number must pass a modulus-11 check digit test.
It is derived because it is computer generated and a check digit is added.

system outputs. For example, if a customer’s last name is truncated, mail would usually
still be delivered; if an email address is truncated, however, it will be returned as not
found. Common lengths of fields are shown below.

Field Length Percentage of Data That Will Fit (U.S.)
Last Name 11 98
First Name 18 95
Company Name 20 95
Street 18 90
City 17 99

7. The type of data—numeric, date, alphabetic, varchar, or character, which is sometimes called
alphanumeric or text data. Varchar data may contain any number of characters, up to a limit
set by the database software. When using varchar, specifying the length is optional. Several of
these formats are shown in Figure 8.7. Character fields may contain a mixture of letters, num-
bers, and special characters. If the element is a date, its format—for example, MMDDYYYY—
must be determined. If the element is numeric, its storage type should be determined.