Symbol 5864 from IEC 60417 - Title/Meaning: Tune, low key Function/description: To identify the function to lower the musical pitch.
Additional information: 
Published in: Amendment 2, 2002,3C/677/FDIS,3C/577/CDV,3C/493/CD,3C(Treviso/Secretariat)10
Own work using: iso.org/obp/graphics/grs/a260bbd6-fc21-4dee-808e-1dbf972a0845 200.png
Vectorization:  Mrmw