N   b   Normal beat

L   b   Left bundle branch block beat

R   b   Right bundle branch block beat

B   b   Bundle branch block beat (unspecified)

A   b   Atrial premature beat

a   b   Aberrated atrial premature beat

J   b   Nodal (junctional) premature beat

S   b   Supraventricular premature or ectopic beat (atrial or nodal)

V   b   Premature ventricular contraction

r   b   R-on-T premature ventricular contraction

F   b   Fusion of ventricular and normal beat

e   b   Atrial escape beat

j   b   Nodal (junctional) escape beat

n   b   Supraventricular escape beat (atrial or nodal)

E   b   Ventricular escape beat

/   b   Paced beat

f   b   Fusion of paced and normal beat

Q   b   Unclassifiable 

?   b   Beat not classified during learning

[   n   Start of ventricular flutter/fibrillation

!   n   Ventricular flutter wave

]   n   End of ventricular flutter/fibrillation

x   n   Non-conducted P-wave (blocked APC)

(   n   Waveform onset

)   n   Waveform end

p   n   Peak of P-wave

t   n   Peak of T-wave

u   n   Peak of U-wave

`   n   PQ junction

'   n   J-point

^   n   (Non-captured) pacemaker artifact

|   n   Isolated QRS-like artifact [1]

~   n   Change in signal quality [1]

+   n   Rhythm change [2]

s   n   ST segment change [2]

T   n   T-wave change [2]

*   n   Systole

D   n   Diastole

=   n   Measurement annotation [2]

"   n   Comment annotation [2]

@   n   Link to external data [3]