Catalogues of classical compositions

This article gives an overview of various catalogues of classical compositions that have come into general use.

Opus numbers

It is certainly possible to identify many musical compositions clearly without the use of a catalog or catalog number. Notably, for centuries the system of opus numbering, where consecutive numbers are assigned to works by the composer or by publishers, has provided a means -- only sometimes effective -- of providing clear identification. The most salient problem with opus numbering is gaps in coverage. Particularly in the days before music publishing had become widespread, it was common for works to be created without being assigned an opus number; and throughout the history of classical music, very few composers gave opus numbers to all of their published works. Here are some of the specific problems.

• Some composers used opus numbers for certain genres of music but not for others (for example, in Handel's time, it was normal to apply opus numbers to instrumental compositions but not to vocal compositions such as operas, oratorios, etc.).
• Some composers gave opus numbers to some of their early compositions but abandoned the practice after some time (examples include Liszt and Hindemith). For Beethoven, it is the opposite: he gave no opus numbers to his earliest work, and only in 1795, at age 24, did he publish his Opus 1, a set of three piano trios.
• Some composers chose to restart the opus numbering sequence. For example, Bartók three times started numbering his works with opus numbers. He stopped the system in 1921 because of the difficulty of distinguishing between original works and ethnographic arrangements, and between major and minor works.
• Some composers used opus numbers in a very erratic manner or were subject to the wishes of their publishers, who for commercial reasons often presented works with opus numbers that bore little relationship to their place in the chronological sequence of the composer's works. In cases such as Schubert and Dvořák, one opus number could refer to a number of different works; or a single work could appear under different opus numbers.
• There are cases where works that a composer chose not to publish were published after their death and assigned very late opus numbers that often give a misleading idea of their order of composition (cases include Mendelssohn, Chopin and Tchaikovsky).
• Other composers simply never used opus numbers at all (examples include Copland, Vaughan Williams and many other 20th-century composers).

In sum, opus numbers are widely used to identify musical compositions, but for the reasons given, they seldom can serve as a comprehensive or reliable way of designating a composer's works. It is for this reason that musicologists have prepared catalogs for the works of many composers.

Musical catalogues

Musical catalogs normally aim to be comprehensive, including all of the works of the composer and incorporating the most up-to-date information about them. Catalogues sometimes go beyond the canonical works to include unpublished sketches, incomplete drafts, and the composer's writings and other non-musical output. In order to avoid confusion and misattribution, catalogs sometime list certain works as only doubtfully attributable to the composer, or include works known to have been spuriously attributed.

Some such catalogues are organised in a single chronological sequence; others are divided into different genres and listed chronologically within each genre; others are alphabetically arranged. A symbol is chosen to represent the catalogue as a whole, and this is usually the initial of the author's or the composer's surname, or an abbreviation of the title of the catalogue itself. In a small number of cases, different symbols apply to different parts of the catalogue.

Among the most famous examples of catalog numbering are:

• the BWV numbers allocated to Johann Sebastian Bach's works in the Bach-Werke-Verzeichnis (Bach Works List) developed by Wolfgang Schmieder. They are also sometimes referred to by their S numbers (after Schmieder)
• the K numbers allocated to Wolfgang Amadeus Mozart's works in the Köchel catalogue, created by Ludwig Ritter von Köchel. In Germany and other parts of Europe, the symbol used is KV, for Köchel-Verzeichnis (Köchel List)
• the numbers allocated to Franz Schubert's works in the Deutsch catalogue, developed by Otto Erich Deutsch

In some cases, both the opus number and the newer catalogue designation are appended to a work. For example, Schubert's first set of Impromptus was published as Op. 90 and is now catalogued as , but concert programmes, CDs and reference works commonly refer to Schubert's "Impromptus, Op. 90, D. 899".

Some catalogues have appendices (, abbreviated as Anh.) for doubtful and/or spurious works, arrangements, etc.

The preparation of a musical catalog is often an enormous task that can take up decades of a scholar's lifetime; for instance, Anthony van Hoboken's catalog of the works of Joseph Haydn runs well over 1000 pages and took from 1934 to 1978 to prepare. Catalogs can also be revised by later scholars, notably the nine editions of the standard Mozart catalog, created by a series of editors stretching from the founding editor Köchel to (most recently) Neal Zaslaw.

Thematic catalogue

A thematic catalogue is an index used to identify musical compositions through the citation of the opening notes (incipit) and/or main theme(s) of the work and/or of its movements or main sections. Such catalogues can be used for many purposes, including as guides to a specific composer's works, as an inventory of a library's holding or as an advertisement of a publisher's output. In addition to the musical identification, a thematic catalogue may contain information such as dates of composition and first performance. Works within a thematic catalogue can be grouped chronologically or by genre.

Thematic catalogues produced as scholarly guides to the works of a particular composer provide a shorthand means of identification for their music. The Bach-Werke-Verzeichnis (BWV) numbering system used for the works of Johann Sebastian Bach is one example.

Multiple catalogues

In a number of cases, more than one catalogue exists, or has existed, for the same composer's works. In most such cases, only one will be considered the current standard catalogue for the purposes of musicological indexing. For example, Liszt's works are now known only by S numbers, from the catalogue by Humphrey Searle, which superseded that created by Peter Raabe, which used R numbers. Older catalogues are included for historiographic purposes.

But there are exceptions to this, such as:

• For Domenico Scarlatti, the Longo catalogue (L numbers) was in use from 1906, and although it has become generally superseded by the 1953 Kirkpatrick catalogue (K or Kk numbers), L numbers are still seen in references. In 1967, Pestelli created a third catalogue (P numbers), which has found acceptance in some places. Because all three symbols are often encountered, there is a concordance to help navigate between them.
• Beethoven's works can appear with an opus number, a WoO number, a Hess number or a Bia number (see Catalogues of Beethoven compositions). Until 1955, the opus numbers that appeared in the Beethoven Gesamtausgabe were used exclusively, but this edition omitted a large number of works. In 1955, Georg Kinsky and Hans Helm produced a listing of works that had not been given opus numbers, and gave them WoO numbers (Werke ohne Opuszahl, or "Works without opus number"). This listing is often referred to as the Kinsky Catalogue. In 1957, Willy Hess produced a new catalogue of Beethoven's unpublished works, which included all or most of the Kinsky Catalogue as well as other pieces; Hess numbers were allocated to this sequence of works. In 1968, Giovanni Biamonti produced the Biamonti Catalogue, which sought to combine and update all pre-existing catalogues. Bia numbers relate to this catalogue.
• Note: The WoO symbol has also been used to classify some other composers' works that were not given opus numbers, such as certain works by Mendelssohn, Schumann and Brahms.
• In Chopin's case, at least four latter-day catalogues vie for prominence: Maurice J. E. Brown (B numbers); Krystyna Kobylańska (KK numbers); Józef Michał Chomiński, whose catalogue is segmented into six parts, each part utilising a different letter (A, C, D, E, P and S); and Chopin National Edition WN numbers. Hence, a work of Chopin can be referred to by its opus number and/or a catalogue number preceded by one of nine letter symbols.
• The cataloguing of Bartók's works is similarly complex. Bartók assigned opus numbers to his works three times. He ended this practice with the Violin Sonata No. 1, Op. 21 in 1921, because of the difficulty of distinguishing between original works and ethnographic arrangements, and between major and minor works. Since his death, three attempts—two full and one partial—have been made at cataloguing. The first, and still most widely used, is András Szőllősy's chronological Sz numbers, from 1 to 121. Denijs Dille subsequently reorganised the juvenilia (Sz. 1–25) thematically, as DD numbers 1 to 77. The most recent catalogue is that of László Somfai; this is a chronological index with works identified by BB numbers 1 to 129, incorporating corrections based on the Béla Bartók Thematic Catalogue.

Ordinary usage

While catalogs exist today for the works of all well-known composers, the practice of scholars and program annotators in identifying works remains mixed -- it is hardly the case that catalog numbers inevitably replace the nomenclatural procedures that prevailed earlier.

First, by custom, many particular works are identified by the formula composers nth genre, where n is the order in which the composer is thought to have composed the works. Thus, the usage ""Mozart's 40th symphony" is more likely to be found than "Mozart's symphony K. 550", particularly in writing addressed to the general public.