Business Metadata: How to Write Definitions
Published: April 1, 2005
Published in TDAN.com April 2005
Introduction: The Importance of Definitions
Many errors and accidents are made/caused by misunderstandings of the meanings of terms used.
How many times have you been in a meeting when the words you heard being said did not match what you thought they were?
Many business decisions are made (and later regretted) due to a misunderstanding of the data, and what the data element used in a report is signifying. Some of these accidents and misunderstandings are large enough to be reported in the media. In prior papers I refer to the Mars Lander episode, where the unit of measure was assumed and not made explicit, miscalculations were made and the equipment was lost. Our businesses are filled with many such examples, although not as costly perhaps, are still quite impactful to the business.
Context is everything. The English language is full of meaning nuances; a word may have multiple meanings based upon the context that it is used.
Business metadata is all about adding context to data. A Dictionary or Glossary is part of business metadata, and it is all about making meaning explicit and providing definitions to business terms, data elements, acronyms and abbreviations. This article is about how to write a good definition. Future articles will be about how to set up a dictionary that will be used.
Definition of a Definition
What is the definition of a definition?
The short form might be: the meaning of a term, formally stated. (From InfoDeveloper toolkit- http://saulcarliner.home.att.net/id/definitions.htm )
Usage note: the term "Term" refers to either a word or phrase that has a definite meaning to the business and is significant enough to be managed by the business both in a glossary and to store data values concerning its occurrence in the real world.
Components of a Definition
The usage of a Controlled Vocabulary (CV) helps software manage glossaries and can also empower enterprise search capabilities. CV acronyms and specialized terms are indicated in italics and parentheses.
Here are the components of a well-written definition. The actual definition text is comprised of items 3, 4 and 5 below.
Definition Usage Notes
Definition Text Structure
As noted above, the three major parts of the definition text are indicated in 3,4 and 5 above. They are:
A good, sound definition must make explicit two out of three of these components. The following example incorporates A and C:
A sleeve is a part of a shirt that
goes over the arm.
Note that "a part of" indicates the broader term or class: Shirt. "Goes over the arm" illustrates a distinguishing characteristic that is a function or use of the sleeve.
PART-OF and TYPE-OF are terms that indicate a broader class relationship. Often the class relationship denoted by IS-A is implied. Sometimes these types of implications can be important to make explicit, sometimes not.
Enumerated, Multiple Meanings
Sometimes a definition can include more than one meaning. This is common in a typical dictionary, and our language is full of such cases. The meaning that the term is used must be derived from the context of the sentence. The multiple meanings are enumerated in a definition description as follows:
There are search tools that prompt the user with "DO you mean..." and lists each possibility corresponding to the different definitions, and assist the user to direct the search.
BT and NT can get tricky. Sometimes a broader term or class is implied, and not important to the scope of the CV. For example, the formal definition of "definition" might be "a group of words that expresses the meaning of a term." A rule of thumb is that all terms used in definition text should be defined in the glossary. However, it is possible to get into a "chicken & egg" thing with either BT's or terms used in the definition. Do you really need to define the broader term "word"?
My answer to this is I would consider certain terms to be "atomic" and well-understood. I am defining "well understood" to mean that the term is in common everyday language, general usage (in general settings and not just in a unique industry) and therefore does not have to be defined. However, be careful! Choose these "well-understood" terms carefully and make sure they really are well-understood. An example of a well-understood term might be "Person". It generally refers to a homo sapien carbon-based life form. However, an example of a poorly understood term is "Customer". You think you know what it means, but do you really? "Customer" should always be explicitly defined for every business.
You obviously get to the place where there are classes (generalizations) that are not useful, and are certainly not worth the effort of defining. As always, the Law of Diminishing Returns applies.
1. A definition should never be a tautology, i.e. defined by itself. For example: "A unicorn is a beast with one horn" tells us nothing because the word unicorn is a compound word, and its parts are Uni = one and corn =horn. More common examples of tautological definitions are:
Customer ID is defined as "The identifier of the Customer".
"Metal is something made of metal".
2. Parts of speech should agree, for example, a noun should be defined with a noun,
verb with a verb, etc. Do not use an adverb phrase like "is when" or "is where" in the definition text.
3. All terms used in the definition should be either defined in the glossary or lexicon themselves
or be considered atomic/basic terms.
4. State distinguishing characteristics precisely.
5. Avoid classes that are too broad. A BT or class should be large enough to include all
members but not too large that it doesn't add any value.
The importance of glossaries and dictionaries cannot be overestimated. Definitions facilitate communication, and help the business make accurate decisions.
In short, definitions should be clear, exact and complete; if not, a spoon can be confused with a knife or fork if the definition reads like this: "a spoon is something to eat with." It is this sort of confusion that costs businesses lots of money from bad business decisions and bad practices. Exposing definitions and making people more aware of the meanings of terms can help the business in a myriad of ways.
This article was also published in March of 2005 on B-Eye-Network.com at http://www.b-eye-network.com/view/734. Check out this publication - It is well worth repeat visits. RSS
Recent articles by Bonnie O'Neil
Bonnie O'Neil -
Bonnie is President of Westridge Consulting, and is an internationally recognized expert on data warehousing and business rules. She is a regular speaker at Meta Data/DAMA Conference, Software Development, Database World, Guide, and the Business Rules Forum; she was the keynote speaker at an international conference on Data Quality in South Africa. She is a founding member of the Guide Business Rules Group (a standards group for business rules) and also the ODTUG Business Rules Summit. She has been involved in data warehousing projects in both Fortune 500 companies and government agencies, and her expertise includes specialized skills such as data quality, profiling, data integration and migration. She is the author of two database books including Oracle Data Warehousing Unleashed, as well as over 40 articles and technical white papers. She is a Certified GIF Architect by Bill Inmon, the father of data warehousing.