SUUNTO Zoop - Manual (Page 103)

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 In sports diving refers to any mix with a higher fraction
of oxygen than standard air.
NOAA United States National Oceanic and Atmospheric
Administration.
No-decompression time The maximum amount of time a diver may remain at a
particular depth without having to make decompression
stops during the subsequent ascent.
No-decompression dive Any dive which permits a direct, uninterrupted ascent
to the surface at any time.
NO DEC TIME Abbreviation for no-decompression time limit.
OEA = EAN = EANx Abbreviation for Oxygen Enriched Air Nitrox.
OLF Abbreviation for Oxygen Limit Fraction.
OTU Abbreviation for Oxygen Tolerance Unit.
Oxygen Tolerance Unit Is used to measure the Whole-Body-Toxicity.