ECG or EKG	Electrocardiography
GPL	Graphite Pencil Lead
PLS	Pencil Lead Solid-type
PLP	Pencil Lead Powder-type
Ag/AgCl	Silver/SilverChloride
ANS	Autonomic Nervous System
HRV	Heart Rate Variability
DCS	Decompression Sickness
FFT	Fast Fourier Transform
PSD	Power Spectrum Density
PVCs	Premature Ventricular Contractions
PACs	Premature Atrial Contractions
meanNN	mean Normal-to-Normal interval
SDNN	Standard Deviation of all NN intervals
RMSSD	(square) Root of the Mean Squared Successive Differences of NN intervals
NN50	number of interval differences of successive NN intervals greater than 50 ms
LF	Low Frequency
HF	High Frequency
HR	Heart Rate