I've noticed that the stand-level summary data (SummaryByStand) features both QMD and QMDS. Based on our conversation, it sounds like QMDS is what we would traditionally think of as stand-level quadratic mean diameter:
QMD = (BA / (TPA * 0.005454154)) ^ 0.5
BA = stand basal area in sqft/ac
TPA = trees per acre
What is QMD, then?