N- Normal beat (displayed as '.' by the Chart-O-Matic, pschart, and psfd)
L- Left bundle branch block beat
R- Right bundle branch block beat
B- Bundle branch block beat (unspecified)
A- Atrial premature beat
a- Aberrated atrial premature beat
J- Nodal (junctional) premature beat
S- Supraventricular premature or ectopic beat (atrial or nodal)
V- Premature ventricular contraction
r- R-on-T premature ventricular contraction
F- Fusion of ventricular and normal beat
e- Atrial escape beat
j- Nodal (junctional) escape beat
n- Supraventricular escape beat (atrial or nodal)
E- Ventricular escape beat
/- Paced beat
f- Fusion of paced and normal beat
Q- Unclassifiable beat
?- Beat not classified during learning
[- Start of ventricular flutter/fibrillation
!- Ventricular flutter wave
]- End of ventricular flutter/fibrillation
x- Non-conducted P-wave (blocked APC)
(- Waveform onset
)- Waveform end
p- Peak of P-wave
t- Peak of T-wave
u- Peak of U-wave
`- PQ junction
'- J-point
^- (Non-captured) pacemaker artifact
|- Isolated QRS-like artifact [1]
~- Change in signal quality [1]
+- Rhythm change [2]
s- ST segment change [2]
T- T-wave change [2]
*- Systole
D- Diastole
=- Measurement annotation [2]
"- Comment annotation [2]
@- Link to external data [3]