Capitalization of key, opus, and number

Music Cataloging at Yale

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Capitalization of key, opus, and numbers

Note: These instructions apply to transcription of information for title (245 field) and contents notes (505 field)
in bibliographic records and 670 field in authority records. They do not apply to uniform titles for music.

See also Capitalization of foreign terms

Key:

In English, the key is capitalized, but not the mode: A major, D minor.
In German¹, D in Dur and M in Moll are capitalized.

In major, the key is capitalized: D-Dur, Fis-Dur
In minor, it is not capitalized: a-Moll, fis-Moll

In other languages,

when given as a letter, the key is capitalized: F majeur, G mineur
but when given as a word, it is not capitalized: fa majeur, sol mineur.

Symphonie Nr. 2 C-Dur op. 61
Konzert für Violoncello und Orchester a-Moll, op. 129
Messe in Es op. 155
Concerto in A minor (Wq 166, H 431) for flute, strings and basso continuo
Sonata per cembalo in sol maggiore
Koncert C dur² pro fagot a smycce

¹This policy is based on a 1977 LC memo stating that, regardless of how a word appears on the publication, for German capitalization, follow Duden Rechtschreibung der deutschen Sprache und der Fremdwörter (Mannheim : Bibliographisches Institut, c1986)
²D in dur is not capitalized here because it is not in German.

Opus:

In German¹, opus is capitalized when spelled out, but not when abbreviated: Opus, op.
In other languages, neither is capitalized.

Vier Fugen Opus 72
String trio opus 45
Symphonies Nr. 2 C-Dur op. 61
Quartet op. 73 for 2 violins, viola, and cello

Numbers:

In German¹, number and its abbreviations are capitalized: Number, Nr., No.
In other languages, it is not: number, no., nr.

Duo concertant für zwei Klarinetten op. 3, Nr. 1
Fantasie für Klavier ohne D-Nummer = Fantasy for piano without "D" number
Quartet No. IV für 2 Violinen, Viola & Violoncello, op. 40
Sonata in D major op. 2 no. 2