atr reference beat annotations man reference beat annotations for selected beats only q1c manually determined boundaries, annotator 1 (second pass) q2c manually determined boundaries, annotator 2 (second pass) qt1 manually determined boundaries, annotator 1 (first pass) qt2 manually determined boundaries, annotator 2 (first pass) pu automatically determined boundaries (based on both signals) pu0 automatically determined boundaries (based on signal 0 only) pu1 automatically determined boundaries (based on signal 1 only)