Air Dive - A dive conducted using air (approximately 21% oxygen & 79% nitrogen) as the breathing gas.

Algorithm - A step-by-step mathematical formula designed to accomplish a particular result (i.e. Dive Time Remaining).

Altitude Dive - A dive made at an elevation above sea level where a different set of no decompression tables is used.

Ascent Rate - the speed that a diver moves vertically toward the surface.

Boot - A protective rubber covering that surrounds an instrument module.

C.Z. - Abbreviation for Caution Zone.

Caution Zone - The yellow section of a bar graph that gives a visual warning of the diver's proximity to projected limits.

Ceiling - See decompression ceiling.

Clean Dive - A dive preceded by 24 hours of no diving activity.

Compartment - A term applied to the hypothetical modeling of nitrogen absorption in the tissues (more accurate than the term 'tissue' because dive computer models have no direct relation to human tissues).

CNS - Abbreviation for the Central Nervous System of the body.

DataLinkTM - A quick disconnect device that facilitates removal of the high pressure instrument hose (and instrument console) from the regulator first stage for protection, transport, storage, or downloading.

DCS - Abbreviation for decompression sickness, i.e. 'the bends'.

DECO - Abbreviation for Decompression.

Decompression Ceiling - The shallowest depth a diver may reach upon ascent without risking decompressing sickness (also see TLBG).

Decompression Stop - The depth(s) at which a diver must pause during ascent to allow absorbed nitrogen to escape naturally from the tissues.

Depth Sensor - An electromechanical device that converts water pressure into an electrical signal, that is converted to a visual depth display.

Diagnostic Mode - The first display seen on dive computers after initial activation during which time a self-check for internal faults and battery voltage is performed.

Display - A visual readout of information.

Dive Log Mode - A computer display of previous dive information.

Dive Time Remaining - A display of the time allowed before a diver must surface based on no decompression status, air time remaining, or oxygen loading.

Elapsed Dive Time - The total time spent underwater during a dive between 5 feet (1.5 meters) on initial descent to 3 feet (1 meter) on final ascent.

FO2 - The fraction (percent / 100) of Oxygen in the breathing gas mixture.

Graphic Diver InterfaceTM - A feature of Oceanic dive computers. Easily understandable color coded bar graphs that indicate diver status; green = normal, yellow = caution, red = danger.

Icon - A small pictorial representation of an operational mode.

LCD - Abbreviation for liquid crystal display, an easily viewed low voltage display found on dive computers.

Maximum Depth - The deepest depth attained during a dive.

Mode - A specific set of functions in a dive computer.

Modular Dive Computer - A dive computer that is not connected to the diver's air supply.

Multiplexing Display - A display on an instrument that alternates to show different information.

Multilevel Dive - A type of dive profile where the diver spends various times at different depths (opposite of a Square Wave dive profile).

Nitrox - A nitrogen-oxygen breathing gas mixture that contains a higher fraction of oxygen than air.

Nitrox Dive - A dive conducted using nitrox (22 to 50% O2) as the breathing gas.

NO DECO - Abbreviation for No Decompression.

NO DECO Time Remaining - The amount of dive time remaining based on no decompression status.

No Decompression - Any part of a dive where the diver can surface without requiring a decompression stop.

O2 Bar Graph - A visual representation of oxygen accumulation on a dive computer display.

OceanGloTM - An Oceanic trade name for an instrument backlight feature.

OceanLinkTM - An Oceanic trade name for a PC downloading product with simulator.

OceanLogTM - An Oceanic trade name for a PC downloading product.

OTU - Abbreviation for oxygen tolerance unit. A Hamilton's Repex method term for oxygen dose.

Out of Range - The point at which a dive computer can no longer supply correct dive information.

Oxygen Tolerance - Dose or exposure to the physiological affects of elevated levels of oxygen.

Oxygen Toxicity - The adverse physiological affects of exposure to elevated levels of oxygen.

Partial Pressure - The proportion of the total gas pressure contributed by a single gas in a mixture of gases.

PDPS - Abbreviation for Pre Dive Planning SequenceTM.

PO2 - Partial pressure of oxygen. The proportion of total pressure of a gas mixture contributed by oxygen.

Pre Dive Planning SequenceTM - A sequence of displays indicating available dive times at 10 foot (3 meter) intervals from 30 to 160 feet (9 to 48 meters( used when dive planning.

Repetitive Dive - Any dive that takes place within 12 hours of a previous dive.

Safety Stop - A depth at which a diver may choose, but is not required, to pause during ascent to allow absorbed nitrogen to escape naturally from the tissues.

Square Wave Dive - A type of dive profile where the entire dive is spent at one depth between descent and asent.

Surface Sequence - An Oceanic term for the sequence of information idplsyed during surface operation.

Tissue Compartment - See Compartment

Tissue Loading Bar GraphTM - A graphic representation of calculated nitrogen absorption displayed alongside a color coded indicator (part of the Graphic Diver Interface).

TLBG - Abbreviation for Tissue Loading Bar GraphTM.

Transducer - An electromechanical device in a dive computer that acts as a depth or pressure sensor.

Transition Period - The first 10 minutes of surface time after ascending above 3 feet (1 meter) from a dive.

VARI - Abbreviation for Variable Ascent Rate IndicatorTM.

Variable Ascent Rate IndicatorTM - A graphic representation of vertical ascent rate (speed) displayed alongside a color coded indicator (part of the Graphic Diver Interface).