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Last revised 1997.

Note: Houghton's Mus class is not the same as the old Widener Mus class, of which there are examples in the Widener transfers section of the Houghton stacks. Guidelines for forming Mus call numbers have varied over time, so there are a number of inconsistencies among items already cataloged; reclassification should not be done unless necessary.

Music is to be classified following the general Houghton classification scheme, with some modifications. The music scheme is similar to that used for cataloging popular works that run into many editions, i.e. no attempt is made to establish the date of the first edition of the work, or to relate other editions to the first edition date. It can be difficult, if not impossible in some cases, to determine edition chronology for scores. Instead, the date of the edition in hand is used.

The classification numbers will enable specific composers, and specific works by those composers, to shelve together and to interfile with works already classified according to the old scheme. If, when classifying a particular work, one finds an edition already classified according to the old scheme, a decision can be made to reclassify the item, but this may not always be necessary and should be discussed on a case-by-case basis.

The first element of the call number is Mus. The usual size designations for regular Houghton call numbers are used, and a small b is used as a prefix for sheet music and non-bulky scores shelved in folders in music boxes, in the same way that it is used before Typ numbers to indicate broadsides and boxed items.

The second element is the Cutter number for the composer. Follow the usual practice for constructing Cutter numbers. For works by 2 or 3 composers published bound, or collected together, cutter for the predominant or most important composer. For anonymous works, use A100.

Distinguishing elements follow the Cutter number. To distinguish between different works by the same composer:

a. Add at the end of the Cutter number, with no space, an upper- and a lower-case letter for the title of the work. Use the first two letters of the first word of the uniform title, or if there is no uniform title, the first word of the title proper (excluding articles). If the title letters conflict with another work by the same composer, add a third, lower-case letter. Optionally, choose a different second lower-case letter if this seems preferable.

b. Add the opus number, if there is one. This will usually be the unique identifying number for the work. The opus number is separated from the Cutter number and title letters by a space, with no period. Do not add a space between "op." and the number itself. For major composers whose works are routinely referred to by thematic catalog numbers, the thematic catalog number is to be preferred.

     Mus.B1223So op.5 uniform title = Sonatas, keyboard instrument, op.5

The opus number is further qualified when necessary, but do not use a slash:

     Mus.B1223So op.5, no.1 not Mus.B1223So op.5/1

When a work has both a serial number and an opus number, use only the opus number.

     Mus.G4698So op.74 Glazunov's piano sonata no.1, op.74

The third element is the full date of the work in hand.

     Mus.B1224Ma.1875 Bach's B-minor mass, published in 1875

If two editions have the same date, add a lower-case "a", "b", "c" etc. at the end of the date. The letter is assigned arbitrarily as the case arises, in alphabetical order. Letters will not be used to distinguish issues and states, nor will they necessarily follow the order of editions. If the date of publication is unknown, use the latest possible date from the bibliographic record, e.g. if the imprint date is [18--?], use "1899" in the call number. For a multi-volume work with a range of publication dates, use the date of the first volume.


If the item is a collection of pieces previously published separately, or a tract volume, follow the general classification scheme: do not add a letter for the title at the end of the Cutter number, precede the date element with a capital "B", and add the last three digits of the publication date, followed by a lower-case letter for the first word of the uniform title, if there is one, or title proper.

     Mus.M8771.B830qa collection of Mozart string quartets, published in 1830

In the case of a tract volume where publication dates differ, use the latest publication date in the collection. One can also use a circa date for the collection, i.e. average date of all the publications in the collection. Each piece in a collection or tract volume will share the same call number, with its precise position within the volume specified in a holdings record note, e.g.: 562 |a No. 4 in a volume with 15 other works by Berlioz. |5 hou

Do not add "no. [x]" to the call number to distinguish a work from others in the same volume, as patrons may confuse this with an opus or serial number.

Scores vs. parts:

If the library has both a score and a separate set of parts, and the call numbers cannot otherwise be distinguished, add a lower-case "p" after the opus, serial, or thematic number in the call number to the parts.

     Mus.G4698Sy op.58p Glazunov's Symphony no.6, op.58, in parts

Thematic catalogs:

Thematic catalogs are classified like bibliographies in the general author scheme.


Serials follow the general Houghton classification scheme.