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9. GLOSSARY
Altitude dive A dive made at an elevation greater than 300 m [1000 ft]
above sea level.
Apnea Absence of breathing. Freedivers are apneic throughout the
duration of their dive.
Ascent rate The speed at which the diver ascends toward the surface.
ASC RATE Abbreviation for ascent rate.
Ascent time The minimum amount of time needed to reach the surface
on a decompression stop dive.
ASC TIME Abbreviation for ascent time.
Ceiling On a decompression stop dive the shallowest depth to
which a diver may ascend
Ceiling Zone On a decompression stop dive the zone between the
ceiling and the ceiling plus 1.8 m [6 ft]. This depth range
is displayed with the two arrows pointing toward each
other (the ”hour glass” icon).
CNS Abbreviation for Central Nervous System toxicity.
Central Nervous System Toxicity
Toxicity caused by oxygen. Can cause a variety of
neurological symptoms. The most important of which is an
epileptic-like convulsion which can cause a diver to drown.
