User's Guide

Term What it means
Floor
The deepest depth during a decompression stop
dive at which decompression takes place.
He%
Helium percentage or helium fraction in the
breathing gas.
MOD
Maximum operating depth of a breathing gas is
the depth at which the partial pressure of
oxygen (PO
2
) of the gas mix exceeds a safe limit.
Multi level dive
A single or repetitive dive that includes time
spent at various depths and whose no
decompression limits are therefore not
determined solely by the maximum depth
attained.
Nitrox (Nx)
In sports diving, refers to any mix with a higher
fraction of oxygen than standard air.
No deco (No
decompression
stop time)
Any dive which permits a direct, uninterrupted
ascent to the surface at any time.
No dec time Abbreviation for no decompression time limit.
OC Open-circuit. Scuba that exhausts all exhaled gas.
OLF%
Oxygen limit fraction. The diver’s current oxygen
toxicity exposure.
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