unwritten -- (based on custom rather than documentation; "an unwritten law"; "rites...so ancient that they well might have had their unwritten origins in Aurignacian times"- J.L.T.C.Spence)
oral, unwritten -- (using speech rather than writing; "an oral tradition"; "an oral agreement")
ad-lib, spontaneous, unwritten -- (said or done without having been planned or written in advance; "he made a few ad-lib remarks")
(TTS Sound)
