6.The terminology used in a given act shall be consistent both internally and with acts already in force, especially in the same field.
Identical concepts shall be expressed in the same terms, as far as possible without departing from their meaning in ordinary, legal or technical language.
In order to aid comprehension and interpretation of a legislative act, the text must be consistent. A distinction can be drawn between formal consistency, concerning only questions of terminology, and substantive consistency, in a broader sense, concerning the logic of the act as a whole.
Consistency of terminology means that the same terms are to be used to express the same concepts and that identical terms must not be used to express different concepts. The aim is to leave no ambiguities, contradictions or doubts as to the meaning of a term. Any given term is therefore to be used in a uniform manner to refer to the same thing and another term must be chosen to express a different concept.
This applies not only to the provisions of a single act, including the annexes, but also to provisions of related acts, in particular implementing acts and all other acts in the same area. In general, terminology must be consistent with the legislation in force.
Words must be used in their ordinary sense. If a word has one meaning in everyday or technical language, but a different meaning in legal language, the phrase must be formulated in such a way as to avoid any ambiguity.
In the interests of precision and to avoid problems of interpretation, it may be necessary to define a term (see Guideline 14).
Consistency of terminology must also be checked with regard to the content of the act itself. There must be no contradictions inherent in the act.
Definitions must be respected throughout the act. Defined terms must be used in a uniform manner and their content must not diverge from the definitions given.