The International Standard Music Number is an identifier.
  A draft ISMN structure and application was presented at the 1987 IAML conference in Amsterdam, then after further discussions at the 1989 IAML conference in Oxford it was decided that the UK, French and German branches should, through their respective national standards bodies (BSI, AFNOR and DIN) file ISMN as an ISO work project
A publication may be assigned both an ISBN and an ISMN

