1. Definitions are provided, where needed, to help users understand the meaning of a concept and decide on its use. There is no requirement that a concept have a definition.

  2. A definition must be consistent with the position of a concept in the hierarchy of concepts.

  3. A definition differs from a scope note, which focuses on what differentiates the concept in question from other concepts.

  4. A concept may have one or more definitions, and each definition may be expressed in one or more languages. Additional definitions need only be corrected or removed if they are in conflict with each other or with the hierarchy. (In GACS 4.0, many concepts have two or three definitions inherited from AGROVOC, CABT, and NALT.)

  5. A definition consists of a narrative explanation -- the actual definition -- plus a mandatory indication of source.

  6. Editors of GACS are encouraged to paraphrase from available sources in writing definitions, taking care not to re-use exact wordings unless the words in question are in the public domain.

  7. Where a definition has been written by a GACS editor, the most salient source of inspiration for the definition should be cited, where applicable, or by default the source cited should be "GACS Editors".

  8. A definition may be quoted from a source in the public domain. Only in rare cases, at the discretion of a GACS editor, should a definition be quoted from a copyrighted source.

  9. A definition should be stated as clearly and objectively as possible without erroneously limiting the concept to a specific discipline.

  10. For definitions inherited from AGROVOC, NALT, or CABT, the original indication of source in AGROVOC, NALT, or CABT, are retained in GACS.

  11. Definitions inherited from AGROVOC, NALT, or CABT that lack such an indication of source will be assigned a default source of "AGROVOC Editors", "NALT Editors", or "CABT Editors". [For discussion: URIs could be minted for teams of editors.]

  12. In cases where a GACS concept has inherited more than one definition, those definitions should be kept as long as they do not repeat or conflict.

  13. The source of a definition should not be cited in-line, in the manner of a journal article, but recorded in a separate source field.

  14. The source of a definition may be indicated in the form of a literal citation. Such citations should supply enough information to identify the version or edition of a source without ambiguity.

  15. The source of a definition may be indicated in the form of a URI which, in the judgement of the GACS editor, is likely to remain stable over time. A URI should not, for example, point to a Web search box or rely on the resolution of an embedded database query.