introductory, preliminary, serving as a prelude or preface. (adjective)
Examples of word prefatory
While others seem to have omitted the important detail of everything, what you put forward prefatory is unconstrained and perfectly stated.
The question-begging leap of logic here is Posner's interjection of "since," when dealing with the connection between the what's known as the prefatory and operative clauses of the 2nd Amendment.
By reading the amendment backwards, Scalia begins with an unfettered right "to keep and bear arms" (look, that's what it says!), and, having established such a right, the mere "prefatory" words of the first half of the amendment become nothing more than window dressing.
The landlady first gave a kind of prefatory yell, which was only a prelude of war-whoop, introductory to that which was to follow.
Legal Adviser Koh alluded to the importance and, within the executive branch and the State Department, the independent weight of that traditional jurisprudence in the beginning of his speech, in which he made some important — but by the press largely not-understood as being important — prefatory framing remarks about the internal jurisprudence of the executive branch.