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Data element definition

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In metadata, a data element definition is a human readable phrase or sentence associated with a data element within a data dictionary that describes the meaning or semantics of a data element.

Data element definitions are critical for external users of any data system. Good definitions can dramatically ease the process of mapping one set of data into another set of data. This is a core feature of distributed computing and intelligent agent development.

There several guidelines to that should be followed when creating high-quality data element definitions.


Using precise words

Common words such as play or run frequently have many meanings. For example the WordNet database documents over 57 different distinct meanings for the word "play" but only a single definition for the term dramatic play. Fewer definitions in a chosen word's dictionary entry is preferable. This minimizes misinterpretation related to a reader's context and background. The process of finding a good meaning of a word is called Word sense disambiguation.

Examples of definitions that could be improved

Here is the definition of "person" data element as defined in the www.w3c.org Friend of a Friend specification*: 

  Person: A person.

Although most people do have an intuitive understanding of what a person is, the definition has much room for improvement. The first problem is that the definition is circular. Note that this definition really does not help most readers and needs to be clarified.

Here is the definition of the "Person" Data Element in the Global Justice XML Data Model 3.0 *: 

  person: Describes inherent and frequently associated characteristics of a person.

Note that once again the definition is still circular. Person should not reference itself. The definition should use terms other than person to describe what a person is.

Here is a more precise but shorter definition of a person: 

  Person: An individual human being.

Note that it uses the word individual to state that this is an instance of a class of things called human being. Technically you might use "homo sapiens" in your definition, but more people are familiar with the term "human being" than "homo sapiens," so commonly used terms, if they are still precise, are always preferred.

Sometimes your system may have cultural norms and assumptions in the definitions. For example if your "Person" data element tracked characters in a science fiction series that included aliens you may need a more general term other than human being. 

  Person: An individual of a sentient species.

See also

References

  1. ISO/IEC 11179-4:2004 Metadata registries (MDR) - Part 4
  2. ISO/IEC Technical Report 20943-1, First edition, 2003-08-01 Information technology — Procedures for achieving metadata registry consistency
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