"A term used in Linguistics and Phonetics to refer to any system of Graphic representation of speech (as in Phonemic notation, where the term transcription is widely used). Specifically it refers to the set of symbols which represent a mode of linguistic analysis, as in the ‘Phrase-structure notation’ in general grammar. An analytic convention, in this sense, which is introduced into an analysis to facilitate the formulation of a statement such as a Rule, is often termed a notational device, e.g. the use of ( ) to indicate optionality in generative syntax."