X00 Subfield $m - Medium of performance for music:

Subfield $m contains term(s) designating the medium of performance used in a uniform title for a work in a name/title heading .

Examples:

100 1#$aBeethoven, Ludwig van,$d1770-1827.$tSonatas,$mpiano.$kSelections

400 1#$aSpeer, Daniel,$d1636-1707.$tSonatas,$mcornetts (2), trombones (3),$rC major

Subfield $m is not used for medium of performance information in a title page title used in a name/title heading.

Example:

400 1#$aRies, Ferdinand,$d1784-1838.$tOctet, opus 128, for piano, clarinet, horn, bassoon, violin, viola, cello & bass

Multiple adjacent elements in a single medium of performance statement are contained in a single subfield $m. Subfield $m is repeated only when medium of performance statements are separated by subelements contained in other subfields.

Example:

100 1#$aArne, Thomas Augustine,$d1710-1778.$tConcertos,$mkeyboard instrument, orchestra.$nNo. 3,$pCon spirito,$mkeyboard instrument

[Subfield $m is repeated due to intervening subelements.]

Additional examples are under the descriptions of subfields $o and $r .

To return:

Use the key.