piano chord
Cm7
C1E♭♭3G5B♭♭7
Minor triad with a minor seventh. The same four notes as a major sixth chord a third above.
What is true of it
Cm7 is C, E♭, G and B♭ — 1, b3, 5 and b7 counted from C.
These are also the notes of E♭6/C and D♯6/C. Which name is right depends on what is underneath and what came before — the notes alone do not decide.
On an instrument that cannot reach all 4, the 5 goes first, in that order.