This supplement to Describing Archives: A Content Standard (DACS) was endorsed by SAA in December 2019. The Guidelines contain extensions to DACS rules and examples of their application for the description of notated music.
2) Archival Description of Notated Music : A Supplement to Describing Archives: A Content Standard (still in draft, August 2018)
These are very helpful companion standards for music, which could be added to the Application Profile:
1) Guidelines for Archival Description of Notated Music : A Supplement to Describing Archives: A Content Standard
https://hcommons.org/deposits/objects/hc:30394/datastreams/CONTENT/content
This supplement to Describing Archives: A Content Standard (DACS) was endorsed by SAA in December 2019. The Guidelines contain extensions to DACS rules and examples of their application for the description of notated music.
2) Archival Description of Notated Music : A Supplement to Describing Archives: A Content Standard (still in draft, August 2018)
https://drive.google.com/file/d/1hjqtTQcQitfzdWkGH9jEE64-vm3E4CHn/view
See especially the Glossary on pp. 111-130 for formats of notated music.
3) Types of composition for use in authorized access points for music: a manual for use with RDA
http://cmc.blog.musiclibraryassoc.org/types-of-composition-for-use-in-authorized-access-points-for-music-a-manual-for-use-with-rda/
The complete list is here:
http://cmc.blog.musiclibraryassoc.org/types-of-composition-for-use-in-authorized-access-points-for-music-complete-list/
4) Optionally, for formal titles and item level description:
Descriptive Cataloging of Rare Materials (Music) - DCRM(M) (2016)
http://rbms.info/files/dcrm/dcrmm/DCRMM.pdf