ISO/IEC 11179 Part 4 Rules and Guidelines for the Formulation of Data Definitions

1. ISO/IEC 11179 Part 4 Rules and Guidelines for the Formulation of Data Definitions February 16, 1999 Lois Fritts Systems Development Center SDC-0055-057-JE-8022

2. Data element definitions and descriptions are often not sufficient to support reuse or multiple users of data Data element names are often not definitive for value domains Data standardization must focus on data element definitions rather than names Challenges

3. Purpose of Definitions The purpose of a data element definition is to define a data element with words or phrases that describe, explain, or make definite and clear its meaning.

4. A data definition shall be: Unique Singular State the concept, not its negative Descriptive phrase or sentence Commonly understood abbreviations Without embedded definitions Data Definition Rules

5. Distinguishable from every other definition within the registry Good - The date when a regulation became effective. The date when collection of the sample began. Poor - The date when the event started. Unique

6. Always expressed in the singular Good - The unique identification number assigned to a facility. Poor - Unique identification numbers assigned to facilities. Singular

7. Cannot exclusively say what it is not Good - A city that is included in a county division. Poor - A city that does not itself represent a county division. Positive, Not Negative

8. Include the essential characteristics of the conceptGood - The name of the individual designated to be the facility’s representative for communications about the facility. Poor - Person to contact. Descriptive

9. Use only commonly known abbreviations Good - The Standard Industrial Classification (SIC) code that represents the economic activity of a company. Poor - The SIC code that represents the economic activity of a company. Avoid Abbreviations

10. Second concept should not appear in the definition Good - The text that describes the method used to calibrate an instrument. Poor - The text that describes the method used to calibrate an instrument. Calibration is the process of rectifying the graduation of quantitative instruments. No Embedded Definitions

11. State the essential meaning of the concept Be precise and unambiguous Be concise Be able to stand alone Be expressed without embedding rationale, functional usage, domain information or procedural information Avoid circular reasoning Use consistent terminology and structure for related definitions Data Definition Guidelines

12. Avoid non-essential characteristics Good - The name of a country where mail is delivered. Poor - The last line of a mail piece that names the country where mail is delivered. Essential Meaning

13. Express exact meaning of the concept Good - The calendar date when latitude and longitude coordinates were determined. Poor - The data collection date. Precise and Unambiguous

14. Comprehensive without extraneous terms Good - The name of the person to contact for clarification of technical information. Poor - The individual whom EPA or State officials may contact if clarification of the information reported on the form is required. Concise

15. Stand alone without further definition Good - The Hydrologic Unit Code (HUC) that represents a geographic area that includes a surface drainage basin or a combination of drainage basins. Poor - The Hydrologic Unit Code (HUC) that represents a cataloging unit. Stand Alone

16. Does not include rationale, functional usage, or procedural information. Good - The distance in meters above or below a reference surface. Poor - The distance above or below a reference surface, measured in meters rather than feet, because meter is an international standard. Without Embedded Rationale

17. A data element should not be defined in the context of another data element Poor - Facility Identification Number -- The number assigned to a facility. Facility -- A site identified by a facility identification number. Avoid Circular Reasoning

18. A common terminology and syntax Good - The code that represents the method used to determine vertical coordinates. The name of the method used to determine vertical coordinates. Poor - The code that represents the method used to determine horizontal coordinates. The method used to determine the latitude and longitude of a place. Consistent with Related Data

19. Use a phrase, not a sentence The name of the country where mail is delivered. Begin the definition by stating the representation class, such as: The name of .. The code that represents… The text that describes … The measure of the ….. The number assigned by….to identify….. The sum, dimension, capacity (quantity) of ….. EDR Definition Syntax

20. Must state exactly the same concept Same - The measure of elevation in meters, above or below a reference datum. (Registry) The vertical distance in meters either above or below a reference surface. (Standard) Different - The height or depth of a facility relative to sea level. EDR Definitions in Context

21. Good definitions promote the standardization and reuse of data elements, leading to data sharing and integration of information systems.