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9. GLOSSARY
Altitude dive A dive made at an elevation greater than 300 m
[1000 ft] above sea level.
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 di
ASC TIME Abbreviation for ascent time.
Ceiling On a decompression stop dive the shallowest depth
to which a diver may ascend based on computer
nitrogen load.
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.
CNS% Central Nervous System toxicity limit fraction. Also
note Oxygen Limit Fraction
Compartment See “Tissue group”.
DAN Divers Alert Network.
DCI Abbreviation for decompression illness.
Decompression Time spent at a decompression stop or range before
surfacing, to allow absorbed nitrogen to escape natu-
rally from tissues.
Decompression range On a decompression stop dive the depth range,
between the fl oor and ceiling, within which a diver
must stop for some time during ascent.
Decompression illness Any of a variety of maladies resulting either directly
or indirectly from the formation of nitrogen bubbles
in tissues or body fl uids, as a result of inadequately
controlled decompression. Commonly called “bends”
or “DCI”.
