The Data Model Resource Book, Volume 3: Universal Patterns for Data Modeling

Silverston c05.tex V2 - 11/21/2008 3:04am Page 190

190 Chapter 5 ■ Types and Categories: the Classification of Data

Types, categories, and taxonomies also may have classifications that are

within (or related to) other classifications.

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For example, if you are classifying

PRODUCT you may have PRODUCT TYPE instances of ‘‘Good’’ and ‘‘Ser-

vice.’’ Then you may further break each of these down into other classifications.

For example, you may break down the ‘‘Service’’ into ‘‘Time and materials

service’’ (for services that are billed by the hour) and ‘‘Deliverable based

service’’ (for services that are billed based upon the delivery of a product).

NOTE

Although we have defined types, categories, and taxonomies, this chapter

mostly focuses on modeling ‘‘types’’ for the level 1 and level 2 patterns and

‘‘categories’’ for the level 3 pattern because we consider a ‘‘category’’ to be more

comprehensive and encompassing than a simple ‘‘type.’’ When we refer to a

classification, this includes ‘‘types’’ and/or ‘‘categories.’’ Taxonomies are made up

of ‘‘types’’ and/or ‘‘categories,’’ so each of the patterns support taxonomies to

different degrees of complexity.

Level 1 Classification Pattern

Averysimplewaytocapturecategoriesandtypesofanentityistouse

attributes — for example, an attribute order type maintaining that an ORDER

is in fact a ‘‘sales order,’’ ‘‘purchase order,’’ ‘‘work order,’’ or a ‘‘manufacturing

order.’’ ...