One Concept Equals One Data Element: A Rule for Developing Data Elements - High-Performance Web Databases: Design, Development, and Deployment - page 79

Exhibit 6-5. Data element name structure.

Prime Word Modifier Class Word

PERSON BIRTH DATE

components that have specific, narrowly defined purposes (e.g., prefabri-
cated parts) cannot be made into as many end-products as the individual
substances of which they are composed. For example, prefabricated com-
ponents cannot be taken apart and have unaffected nails, screws, pipes,
glue, lumber, and plaster. Each of these ingredients has been altered by the
process of constructing the prefabricated part, and they cannot return to
their original state. Similarly, melded data chunks that are created for spe-
cific narrow purposes cannot be used to create as many end-products as
data elements can. In addition, the benefits of flexible data elements that
comply with the one-concept-equals-one-data-element rule apply not only
when using them but when maintaining them. It is easier to make modifica-
tions to data elements than it is to change melded data chunks.

THE DATA ELEMENT NAMING PROCESS

Data Element Names

Most data element naming standards agree on a basic data element
name structure: one prime word (which represents the thing about which
the data is being collected), one class word (which provides the category
of information and some indication of the format and structure), and one or
more modifiers (i.e., adjectives that modify the prime word or class word)
to make the data element name unique and meaningful. Exhibit 5 contains
an example of this structure.

Existing naming standards, however, fail to produce data elements that
comply with the one-concept-equals-one-data-element rule for at least two
reasons: they do not provide guidelines for choosing appropriate modifiers,
and they imply that developing data element names is the correct first step.

Modifiers

One of the deficiencies in data element standardization procedures is
that they focus on naming data elements while other important data ele-
ment development aspects are underrepresented. Some data element nam-
ing standard designers claim that using entity names from a data model as
prime words ensures that the data element includes only one concept.
Using entity names from a data model for the prime words is insufficient to
ensure that a data element complies with the one-concept-equals-one-data-
element rule. A naming convention of this type unnecessarily relies on the
accuracy and completeness of the data model. Data element development