1. Lois Fritts SAIC January 17, 2000 Open Forum on Metadata Registries Santa Fe, NM SDC-0002-021-JE-2022

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

3. SDC-0002-021-JE-2022 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. SDC-0002-021-JE-2022 Data Definition Rules v A data definition shall be: u Unique u Singular u A statement of concept, not its negative u A descriptive phrase or sentence u Commonly understood abbreviations u Without embedded definitions

5. SDC-0002-021-JE-2022 v 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 something started. Unique

6. SDC-0002-021-JE-2022 Singular v Always expressed in the singular. Good - The unique identification number assigned to a facility. Poor - Unique identification number assigned to facilities.

7. SDC-0002-021-JE-2022 Positive, Not Negative v Cannot exclusively say what it is not. Good - The name of a facility that is recognized by the local community as the commercial name. Poor - The name of a facility that is not the legal name.

8. SDC-0002-021-JE-2022 Descriptive v Include the essential characteristics of the concept. Good - The name of the individual designated to be the facility’s representative for communications about the facility. Poor - Person to contact.

9. SDC-0002-021-JE-2022 Avoid Abbreviations v 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.

10. SDC-0002-021-JE-2022 No Embedded Definitions v 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, where calibration is the process of rectifying the graduation of quantitative instruments.

11. SDC-0002-021-JE-2022 Data Definition Guidelines v State the essential meaning of the concept. v Be precise and unambiguous. v Be concise. v Be able to stand alone. v Be expressed without embedding rationale, functional usage, domain information or procedural information. v Avoid circular reasoning. v Use consistent terminology and structure for related definitions.

12. SDC-0002-021-JE-2022 Essential Meaning v 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.

13. SDC-0002-021-JE-2022 Precise and Unambiguous v Express exact meaning of the concept. Good - The calendar date when latitude and longitude coordinates were determined. Poor - The data collection date.

14. SDC-0002-021-JE-2022 Concise v Comprehensive without extraneous terms. Good - The name of the person to contact for clarification of technical information. Poor - The individual EPA or State officials may contact if clarification of the information reported on the form is required.

15. SDC-0002-021-JE-2022 Stand Alone v Stand alone without further definition. Good - The Hydrologic Unit Code (HUC) that represents a surface drainage basin or a combination of drainage basins. Poor - The Hydrologic Unit Code (HUC) that represents a cataloging unit.

16. SDC-0002-021-JE-2022 Without Embedded Rationale v 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 unit of measure.

17. SDC-0002-021-JE-2022 Avoid Circular Reasoning v 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–The site identified by a facility identification number.

18. SDC-0002-021-JE-2022 Consistent with Related Data v 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 name of the method used to determine the latitude and longitude of a place.

19. SDC-0002-021-JE-2022 Example Definition Syntax v Use a phrase, not a sentence. The name of the country where mail is delivered. v 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….

20. SDC-0002-021-JE-2022 Definitions in Context v 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.

21. Good definitions promote the standardization and reuse of data elements, leading to data sharing and integration of information systems. SDC-0002-021-JE-2022