 For a notation to perform this function, it must meet certain strict syntactic and semantic requirements (Goodman 1968: chapter 4). Goodman thinks that these requirements are met by most elements in Western modern musical notation, with the important exceptions of dynamics, tempo indications, and others, which therefore become irrelevant to the work’s identity (but see Webster 1971). A performance counts as an instance of a given work if and only if it complies with its score, and a work of music is nothing other than the class of performances compliant with that score.