piano chord
Bm7
B1D♭3F♯5A♭7
Minor triad with a minor seventh. The same four notes as a major sixth chord a third above.
What is true of it
Bm7 is B, D, F♯ and A — 1, b3, 5 and b7 counted from B.
These are also the notes of D6/B. 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.