Key to ARCO Numeric System: A Comprehensive Listing of Aaron Copland Numbered Music Compositions
Manscripts and Copies of Manuscripts:
All manuscripts and copies of manuscripts (i.e., ozalids, photocopies, and photostats) are assigned whole ARCO numbers and/or whole numbers with decimal point and number. Examples: Billy the Kid complete ballet, ms., [ARCO 33]; or Billy the Kid complete ballet, ms. (ozalid), [ARCO 33.1].
Published Works:
Published works are assigned ARCO numbers followed by a lower case letter, or edition suffix. In most cases (but not all), the lower case "a" indicates first editions. Subsequent editions are assigned suffixes according to the date of publication or copyright. Examples: Billy the Kid complete ballet, [ARCO 33a]; or Billy the Kid complete ballet (published 1950), [ARCO 33c]. If a work includes a score and a set of parts, separate citations are created for each unless there are less than eight parts. The ARCO number for a set of parts will be essentially the same as the accompanying score, but can be identified by a doubled edition suffix. Examples: Billy the Kid score for complete ballet, [ARCO 33a]; Billy the Kid orchestral parts, [ARCO 33aa]. In cases where there are multiple copies of a published edition, the marked or annotated copy is designated as Copy 1; however, only subsequent copies (i.e., Copy 2, Copy 3, etc.) bear the "Copy" designator.
Adaptations and Transcriptions:
Some of Copland's works have been adapted or transcribed for performance by groups of varying sizes (or genres). For instances, the work Billy the Kid has been adapted for performance by orchestra alone (large and small), concert band, and transcribed for two pianos as well as for piano solo. Different versions of a pieces are assigned an ARCO number followed by a hyphen, and an upper case letter, or genre indicator. Examples: Billy the Kid ballet suite, ms., [ARCO 33-A]; or Billy the Kid for two pianos, ms. sketches, [ARCO 33-B.3], etc. This scheme also works for published editions: the genre indicator is followed by an edition suffix. Examples: Billy the Kid for piano solo, [ARCO 33-Ca]; or Billy the Kid for violin and piano (published 1955), [ARCO 33-Gc].
As mentioned, the number assignments and genre indicators are those of the composer. Some adjustments have been made only to render items easily accessible to researchers and retrieved/returned by Music Division staff.