|The definition shall have the same grammatical form as the term.
| The preferred structure of a definition is: a basic part stating the class to which the concept belongs, and another part enumerating the characteristics that distinguish the concept from other members of the class.
|Unless there is a specific reason, the definition shall not begin with an article.
|Preferred term(s) … Lowercase, except for uppercase characters that constitute part of the normal spelling of the term in a running text.
|Preferred term(s) … Parentheses and square brackets shall be used only if they constitute part of the normal written form of the term. They shall not be used to show alternative terms.
|In general, the term shall be presented in its basic grammatical form, i.e. a noun in the singular; an adjective (in inflectional languages) in its uninflected form; a verb in the infinitive (without the word "to" in English).
|If a given term designates more than one concept, each concept shall be treated in a separate entry, particularly in multilingual terminology standards.
|If national variants are used within the same language (e.g. one concept but two different terms or one term but with different spelling), the variants shall be marked.
|Abbreviated forms … On a separate line in a vertical arrangement.
|Word class shall be indicated whenever there is a risk of misunderstanding. It shall be shown by one of the designations "noun," "adj" (for adjective) or "verb."
|In languages that classify nouns by gender, the gender of nouns shall be indicated. It shall be shown by one of the designations "m," "f" or "n" for masculine, feminine or neuter respectively. In coumpound terms, the gender of the compound shall be shown at the end of the term.
|If one term designates several concepts, it is necessary to indicate the subject field to which each concept belongs.
|The definition shall consist of a single phrase describing the concept denoted by the term.
|If a definition has been taken from another normative document, a reference shall be added between square brackets after the definition.
|If an alphabetical terminology standard is unavoidable, each non-preferred term shall be entered in its normal place in the alphabetical sequence, together with a reference to the preferred term.
|Cross-references given for comparison shall be introduced by "cf.."
|Generally, one begins by defining superordinate concepts. When drafting a new definition, use shall be made of basic concepts or concepts defined elsewhere in the document as far as possible.
|The substitution principle shall be used to test the validity of a definition. A definition is valid if it can replace a designation in a text without loss of or change in meaning.