1. Background

When the ISBN proved to be a comprehensive rationalisation tool for the book trade, the music publishers also advocated a similar standard number for printed music. A retarding element in the discussion was the controversy over whether a simple identification number would suffice or a bibliographic code was needed which represented, for example, also the link between the score and the individual parts.

When the International Association of Music Librarians, Archives and Documentation Centres (IAML), UK Branch, addressed the International ISBN Agency with a proposal for a ten-digit number without bibliographic codes, this scheme was published in "ISBN Review" and immediately found wide acclaim. ISO / TC 46 accepted the proposal officially as a work project, and an agreement between European and American publishers and specialists was reached at a meeting of European and North American experts in Ottawa after intensive discussions. The main arguments to discard the previous idea of a 13-digit number were the long-standing experience with the ISBN and the option of incorporating a ten-digit number in the 13-digit international bar code system by simply extending the ISBN system. The ISMN draft was processed by ISO working groups in record time and was officially available as of the end of 1993 when the standard was published in Geneva.

In principle ISMN may be considered a sub-set of the ISBN. In order to prevent any confusion between the two ten-digit sets of numbers, a few differences to the ISBN system were introduced into the ISMN scheme:

• the first digit is the constant "M,"
• there is no group number on the grounds that music is international,
• the check digit is calculated according to the modulus 10.

While both numbers may be integrated in the 13-digit bar code system, they are usually used without any bar code prefix, e.g., for ordering, bibliographic identification and internal processing purposes. Therefore these differences are necessary in order to avoid confusion.

The ISMN offers the options of a complete rationalisation of music publishing and trade as well as music libraries.