# GLOSSARY OF ABBREVIATIONS AND ACRONYMS
## A

| A | amplitude; augmentation; away (altitude intercept); Arctic/Antarctic (air mass) |
| a | semimajor axis |
| a | altitude intercept (Ho~Hc); altitude factor (change of altitude in 1 minute of time from meridian transit); assumed |
| ABAND | abandoned |
| AC | alternating current; altocumulus |
| ACC | Antarctic Circumpolar Current |
| add'l | additional |
| ADF | automatic direction finder |
| ADIZ | air defense identification zone |
| AEB | acquisition exclusion boundary |
| AERO | aeronautical |
| AF | audio frequency |
| AFC | automatic frequency control |
| AGC | automatic gain control |
| AISM | Association Internationale de Signalisation Maritime (International Association of Lighthouse Authorities) |
| aL | assumed latitude |
| Al., Alt, | alternating (light) |
| A.L.R.S. | Admiralty List of Radio Signals. |
| am | amber |
| AM | amplitude modulation |
| AM | ante meridian (before noon) |
| Anch | anchorage |
| antilog | antilogarithm |
| AP | assumed position |
| approx. | approximate, approximately |
| ARPA | automatic radar plotting aid |
| ASAM | anti-ship action message |
| ASF | Additional Secondary Phase Factor |
| AT | atomic time |
| AU | astronomical unit |
| AUSREP | Australian Ships Reporting System |
| al | assumed longitude |

## B

| B | atmospheric pressure correction (altitude); bearing, bearing angle |
| Bdy Mon | boundary monument |
| BFO | beat frequency oscillator |
| BIH | Bureau Internationale de l’Heure |
| BIPM | International Bureau of Weights and Measures |
| bk | broken |
| bkw | breakwater |
| bl | blue |
| BM | bench mark |
| Bn | beacon |
| Bpgc | bearing per gyrocompass |
| br | breakers |
| Brg. | bearing (as distinguished from bearing angle). |
| bu | blue |

## C

| C | Celsius (centigrade) |
| C | chronometer time |
| C | compass (direction) |
| C | correction |
| C | course |
| C | course angle |
| C | can |
| C | cylindrical |
| C | cove |
| CALM | catenary anchor leg mooring |
| CB | compass bearing |
| CBDR | constant bearing, decreasing range |
| CC | compass course |
| CC | chronometer correction |
| CCIR | International Radio Consultative Committee |
| CCU | Consultative Committee for Units of the International Committee of Weights and Measures (CIPM) |
| CCZ | Coastal Confluence Zone |
| cd | candela, candelas |
| CD | chart datum |
| CD-ROM | compact disk-read only memory |
| CG | Coast Guard |
| CE | chronometer error |
| CE | compass error |
| CFR | Code of Federal Regulations |
| cec | centicycle |
| cel | centilane |
| CEP | circular probable error |
| CES | coast earth station |
| CFR | Code of Federal Regulations |
| CGPM | General Conference of Weights and Measures |
| CH | compass heading |
| CIPM | International Committee of Weights and Measures |
| Cl | clearance |
| cm | centimeter(s) |
| CMG | course made good |
| Cn | course (as distinguished from course angle) |
| co | coral |
| co- | the complement of (90° minus) |
| COA | course of advance |
| COE | Committee on ECDIS (IHO) |
| COG | course over ground |
| coL | colatitude |
| colog | cologarithm |
| corr. | correction |
| cos | cosine |
| cot | cotangent |
| cov | coversine |
| CPA | closest point of approach |
| CPE | circular probable error |
| Cpgc | course per gyrocompass |
| cps | cycles per second |
| Cpsc | course per standard compass |
| Cp stg c | course per steering compass |
| CPU | central processing unit |
| crs | course |
| CRT | cathode-ray tube |
| csc | cosecant |
| cup | cupola |
| Cus Ho | customs house |
| CW | continuous wave |
| CZn | compass azimuth |

## D

| D | deviation |
| D | dip (of horizon) |
| D | distance |
| D | destroyed |
| d | declination (astronomical) |
| d | altitude difference |
| d | declination change in 1 hour |
| dA | difference of longitude (time units) |
| DC | direct current |
| deg. | degree(s) |
| Dec. | declination |
| Dec. Inc. | declination increment |
| Dep. | departure |
| destr | destroyed |
| Dev. | deviation |
| DG | degaussing |
| DGPS | differential global positioning system |
| DHQ | mean diurnal high water inequality |
| Dia | diaphone |
| diff. | difference |
| Dist. | distance |
| D. Lat. | difference of latitude |
| DLo | difference of longitude (arc units) |
| DLQ | mean diurnal low water inequality |
| dm | decimeters |
| DMAHTC | Defense Mapping Agency Hydrographic/Topographic Center |
| DNC | digital navigation chart |
| dol | dolphin |
| DR | dead reckoning |
| DR | dead reckoning position |
| DRE | dead reckoning equipment |
| DRM | direction of relative movement |
| DRT | dead reckoning tracer |
| Ds | dip short of horizon |
| DSC | digital selective calling |
| DSD | double second difference |
| DSVL | doppler sonar velocity log |
| dur. | duration |
| DW | Deep Water Route |
| DZ | danger zone |

## E

| E | east |
| e | base of Naperian logarithms |
| e | origin of own ship’s true vector |
| e | eccentricity |
| EBL | electronic bearing line |
| ECD | envelope to cycle difference |
| ECD | envelope to cycle discrepancy |
| EC | electronic chart |
| ECDB | electronic chart data base |
| ECDIS | electronic chart display and information system |
| ED | existence doubtful |
| EDD | estimated date of departure |
| EEZ | exclusive economic zone |
| EGC | enhanced group calling |
| EHF | extremely high frequency |
| E. Int. | equal interval |
| E. Int. | isophase |
| EM | electromagnetic (underwater log) |
| em | other ship’s true vector |
| ENC | electronic navigation chart |
| ENCDB | electronic navigation chart data base |
| EP | estimated position |
| EPIRB | Emergency Position Indicating Radiobeacon |
| EPROM | erasable programmable read only memory |
| Eq.T | equation of time |
| er | own ship’s true vector |
| ET | Ephemeris Time |
| ETA | estimated time of arrival |
| ETD | estimated time of departure |
| Exting | extinguished |

## F

| F | Fahrenheit |
| F | fast |
| F | longitude factor |
| F | phase correction (altitude) |
| F | fixed (light) |
| f | latitude factor |
| f | flattening or ellipticity |
| F.Fl. | fixed and flashing |
| Fl. | flashing (light) |
| Fl. (2) | group flashing (light) |
| Fl. (2+1) | composite group flashing (light) |
| fm(s) | fathom(s) |
| FM | frequency modulation |
| Fog Det. | fog detector |
| Fog Sig. | fog signal |
| ft. | foot, feet |
| FTC | fast time constant |

## G

| G | Greenwich |
| G | Greenwich meridian (upper branch) |
| G | grid (direction) |
| G | gravel |
| G | green |
| g | acceleration due to gravity |
| g | Greenwich meridian (lower branch) |
| GAT | Greenwich apparent time |
| GB | grid bearing |
| GC | grid course |
| GCLWD | Gulf Coast Low Water Datum |
| GDOP | geometric dilution of precision |
| GE | gyro error |
| GH | grid heading |
| GHA | Greenwich hour angle |
| GMDSS | Global Maritime Distress and Safety System |
| GMT | Greenwich mean time |
| Gp. Fl. | group flashing |
| GP | geographical position |
| GPS | Global Positioning System |
| Gr. | Greenwich |
| GRI | group repetition interval |
| GST | Greenwich sidereal time |
| GV | grid variation |
| GZn | grid azimuth |

## H

| h | altitude (astronomical) |
| h | height above sea level |
| h | hours |
| ha | apparent altitude |
| Hc | computed altitude |
| Hdg. | heading |
| HE | heeling error |
| HE | height of eye |
| HF | high frequency |
| hf | height above sea level in feet |
| HHW | higher high water |
| HHWI | higher high water interval |
| Hk | hulk |
| HLW | higher low water |
| HLWI | higher low water interval |
| hm | height above sea level in meters |
| Ho | observed altitude |
| Hor | horizontal |
| Hor Cl | horizontal clearance |
| HP | horizontal parallax |
| Hp | precomputed altitude |
| Hpgc | heading per gyrocompass |
| Hpsc | heading per standard compass |
| Hp stg c | heading per steering compass |
| hr | rectified (apparent) altitude |
| hr. | hour, hrs., hours |
| hs | sextant altitude |
| HSD | high speed data |
| ht | tabulated altitude |
| HW | high water |
| H.W.F.&C. | high water full and change |
| HWI | high water interval |
| HWI | mean high water lunitidal interval |
| HWQ | tropic high water inequality |
| Hz | Hertz |

## I

| I | instrument correction |
| i | inclination (of satellite orbit) |
| IALA | International Association of Lighthouse Authorities |
| IAU | International Astronomical Union |
| IC | index correction |
| ICW | Intracoastal Waterway |
| IGLD | International Great Lakes Datum |
| IHB | International Hydrographic Bureau |
| IHO | International Hydrographic Organization |
| IMO | International Maritime Organization |
| in. | inch, inches |
| INM | International Nautical Mile |
| INMARSAT | International Maritime Satellite Organization |
| INS | inertial navigation system |
| int. | interval |
| Int. Qk. | Interrupted quick flashing |
| ION | Institute of Navigation |
| I.Q. | interrupted quick flashing |
| IR | interference rejection |
| IRP | image-retaining panel |
| ISLW | Indian spring low water |
| ISO | International Order of Standardization |
| ISO | isophase (light) |
| ITU | International Telecommunications Union |
| IUGG | International Union of Geodesy and Geophysics |
| I.U.Q. | interrupted ultra quick flashing |
| I.V.Q. | interrupted very quick flashing |
| IWW | Intracoastal Waterway |

## J – K – L

| J | irradiation correction (altitude) |
| K | Kelvin (temperature) |
| kHz | kilohertz |
| km | kilometer, kilometers |
| kn | knot, knots |
| L | latitude |
| L | lower limb correction for moon |
| l | difference of latitude |
| l | logarithm, logarithmic |
| LAN | local apparent noon |
| LANBY | large automatic navigational buoy |
| LASH | lighter aboard ship |
| LAT | local apparent time |
| lat. | latitude |
| LF | low frequency |
| L.Fl. | long flashing |
| LHA | local hour angle |
| LHW | ower high water |
| LHWI | lower high water interval |
| LL | lower limb |
| LLW | lower low water |
| LLWD | lower low water datum |
| LLWI | lower low water interval |
| Lm | middle latitude |
| Lm | mean latitude |
| LMT | local mean time |
| LNB | large navigational buoy |
| LNG | liquified natural gas |
| LPG | liquified petroleum gas |
| Log | logarithm, logarithmic |
| Loge | natural logarithm (to the base e) |
| Log10 | common logarithm (to the base 10) |
| Long. | longitude> |
| LOP | line of position |
| LST | local sidereal time |
| Lt. | light |
| Lt Ho | light house |
| Lt V | light vessel |
| LW | low water |
| LWD | low water datum |
| LWI | low water interval |
| LWI | mean low water lunitidal interval |
| LWQ | tropic low water inequality |

## M

| M | celestial body |
| M | meridian (upper branch) |
| M | magnetic (direction) |
| M | meridional parts |
| M | nautical mile, miles |
| M | other ship |
| m | meridian (lower branch) |
| m | meridional difference |
| m | meter,(s) |
| m | U.S. survey mile, miles |
| m | end of other ship’s true vector |
| m | minutes |
| mag. | magnetic |
| mag. | magnitude |
| MARAD | United States Maritime Administration |
| MB | magnetic bearing |
| mb | millibar(s) |
| MC | magnetic course |
| mc | megacycle, megacycles |
| mc | megacycles per second |
| MC&G | mapping, charting and geodesy |
| MCPA | minutes to closest point of approach |
| Mer. Pass. | meridian passage |
| MF | medium frequency |
| MGRS | military grid reference system |
| MH | magnetic heading |
| MHHW | mean higher high water |
| MHHWL | mean higher high water line |
| MHW | mean high water |
| MHWI | mean high water lunitidal interval |
| MHWL | mean high water line |
| MHWN | neap high water or high water neaps |
| MHWS | mean high water springs |
| MHz | megahertz |
| mi. | mile, miles |
| mid | middle |
| min. | minute(s) |
| MLLW | mean lower low water |
| MLLWL | mean lower low water line |
| MLW | mean low water |
| MLWI | mean low water lunitidal interval |
| MLWL | mean low water line |
| MLWN | neap low water or low water neaps |
| MLWS | mean low water springs |
| mm | millimeters |
| Mn | mean range of tide |
| mo | month(s) |
| MODU | mobile offshore drilling unit |
| Mon | monument |
| Mo.(U) | Morse Uniform (light) |
| mph | miles per hour |
| MPP | most probable position |
| MRI | mean rise interval |
| MRM | miles of relative movement |
| ms | millisecond(s) |
| MSC | Military Sealift Command |
| MSI | maritime safety information |
| MSL | mean sea level |
| MTI | moving target indication |
| MTL | mean tide level |
| MWL | mean water level |
| MWLL | mean water level line |
| MZn | magnetic azimuth |

## N

| N | north |
| N | nun |
| n | natural (trigonometric function) |
| Na | nadir |
| NAD | North American Datum |
| NASA | National Aeronautics and Space Administration |
| NAUTO | nautophone |
| NAVSAT | Navy Navigation Satellite System |
| NAVSSI | navigation sensor system interface |
| NBDP | narrow band direct printing |
| NBS | National Bureau of Standards |
| NCS | network coordination station |
| NESS | National Earth Satellite Service |
| NGVD | National Geodetic Vertical Datum |
| NLT | not less than (used with danger bearing) |
| n. mi. | nautical mile(s) |
| NM | nautical mile, miles |
| NM | notice to mariners |
| NMEA | National Marine Electronics Association |
| NMT | not more than (used with danger bearing) |
| NNSS | Navy Navigation Satellite System |
| NOAA | National Oceanic and Atmospheric Administration |
| NOS | National Ocean Service |
| NRML | new relative movement line |
| NtM | notice to mariners |
| NWS | National Weather Service |

## O

| Obsc | obscured |
| Obs Spot | Observation spot |
| Obstr | obstruction |
| Oc. | occulting |
| Oc.(2) | group occulting |
| Oc.(2+1) | composite group occulting |
| Occas | occasional |
| ODAS | oceanographic data acquisition systems |
| Or | orange |
| OTC | officer in tactical command |
| OTSR | Optimum Track Ship Routing |

## P

| P | atmospheric pressure |
| P | parallax |
| P | planet |
| P | pole |
| P | pillar |
| p | departure |
| p | polar distance |
| PA | position approximate |
| PC | personal correction |
| PC | personal computer |
| PD | position doubtful |
| PCA | polar cap absorption |
| PCD | polar cap disturbance |
| PCP | potential point of collisio |
| pgc | per gyrocompass |
| P in A | parallax in altitude |
| PM | pulse modulation |
| PM | post meridian (after noon) |
| Pn | north pole |
| Pn | north celestial pole |
| PPC | predicted propagation correction |
| PPDB | point positioning data base |
| PPI | plan position indicator |
| PRF | >pulse repetition frequency |
| Priv | private |
| Priv | privately |
| PROHIB | prohibited |
| PRR | pulse repetition rate |
| Ps | south pole |
| Ps | south celestial pole |
| psc | per standard compass |
| p stg c | per steering compass |
| Pub. | publication |
| PV | prime vertical |
| Pyl | pylon |

## Q

| Q | quick flashing |
| Q(3) | group quick flashing (3 flashes) |
| Q(6)+L.Fl. | group quick flashing (6 flashes) plus a long flash |
| Q | Polaris correction |
| QQ' | celestial equator |

## R

| r | end of own ship’s true vector |
| R | Rankine (temperature) |
| R | refraction |
| R | own ship |
| R | red |
| R | rocky |
| R | coast radio station |
| RA | right ascension |
| RACON | radar transponder beacon |
| rad | radian(s) |
| RB | relative bearing |
| R Bn | radiobeacon |
| RCC | Rescue Coordination Center |
| RDF | radio direction finder |
| RDF | RDF station |
| Rep. | reported |
| rev. | reversed |
| RF (rf) | radio frequency |
| R Fix | running fix |
| rk | rock, rocky |
| RLG | ring laser gyro |
| rm | relative DRM-SRM vector |
| R Mast | radio mast |
| RORO | roll-on/roll-off |
| RML | relative movement line |
| RMS | root mean square |
| RSS | root sum square |
| RTCM | Radio Technical Commission for Maritime Services |
| RZn | relative azimuth |

## S

| s | second(s) |
| S | sea-air temperature difference correction |
| S | slow |
| S | south |
| S | set |
| S | speed |
| S | sand |
| SALM | single anchor leg mooring |
| SAM | system area monitor |
| SAR | search and rescue |
| SART | search and rescue radar transponder |
| SBM | single buoy mooring |
| SD | semidiameter |
| SD | sounding doubtful |
| sec | secant |
| sec. | second, seconds |
| semidur. | semiduration |
| SENC | system electronic navigation chart |
| SES | ship earth station |
| SF | Secondary Phase Factor |
| SH | ship’s head (heading) |
| SHA | sidereal hour angle |
| SHF | super high frequency |
| SI | International System of Units |
| SID | sudden ionospheric disturbance |
| sin | sine |
| SINS | Ships Inertial Navigation System |
| SLD | sea level datum |
| SMG | speed made good |
| SNR | signal-to-noise ratio |
| SOA | speed of advance |
| SOG | speed over ground |
| SOLAS | Safety of Life at Sea Convention |
| SP | spire |
| SP | spherical |
| SPA | sudden phase anomaly |
| SPM | single point mooring |
| SRM | speed of relative movement |
| SS | signal station |
| U.S. Sur M | U.S. Survey mile(s) |
| sub, subm | submerged |

## T

| T | air temperature correction (altitude) |
| T | table |
| T | temperature |
| T | time |
| T | toward (altitude intercept) |
| T | true (direction) |
| t | dry-bulb temperature |
| t | elapsed time |
| t | meridian angle |
| t' | wet-bulb temperature |
| tab. | table |
| TAI | International Atomic Time |
| tan | tangent |
| TB | true bearing |
| TB | turning bearing |
| TB | air temperature atmospheric pressure correction (altitude) |
| TC | true course |
| TCA | time of satellite closest approach |
| TCPA | time to closest point of approach |
| TcHHW | tropic higher high water |
| TcHHWI | tropic higher high water interval |
| TcHLW | tropic higher low water |
| TcLHW | tropic lower high water |
| TcLLW | tropic lower low water |
| TcLLWI | tropic lower low water interval |
| TD | time difference (Loran C) |
| Tel | telephone |
| Tel | telegraph |
| TG | time difference of groundwaves from master and secondary (slave) stations (Loran) |
| TGS | time difference of groundwave from master and skywave from secondary (slave) station (Loran) |
| TH | true heading |
| TMG | track made good |
| TOD | time of day (clock) |
| Tk | tank |
| TR | track |
| Tr | transit |
| Tr | tower |
| Ts | time difference of skywaves from master and secondary (slave) stations (Loran) |
| TSG | time difference of skywave from master and groundwave from secondary (slave) station (Loran) |
| TSS | traffic separation scheme |
| TZn | true azimuth |

## U

| U | upper limb correction for moon |
| UHF | ultra high frequency |
| UL | upper limb |
| Uncov | uncovers |
| UPS | Universal Polar Stereographic |
| U.Q. | ultra quick flashing |
| USGS | United States Geodetic Survey |
| USWMS | Uniform State Waterway Marking System |
| UT | Universal Time |
| UT0 | Universal Time 0 |
| UTl | Universal Time 1 |
| UT2 | Universal Time 2 |
| UTC | Coordinated Universal Time |
| UTM | Universal Transverse Mercator |

## V

| V | variation |
| V | vertex |
| v | excess of GHA change from adopted value for 1 hour |
| var. | variation |
| vel | velocity |
| Ver | vertical |
| VHF | very high frequency |
| VHSD | very high speed data |
| Vi | violet |
| VLCC | very large crude carrier |
| VLF | very low frequency |
| vol | volcano |
| vol | volcanic |
| VPF XX | vector product format |
| V.Q. | very quick flashing |
| V.Q.(3) | group very quick flashing |
| VRM | variable range marker |
| VTS | vessel traffic service |

## W

| W | west; white |
| WARC | World Administrative Radio Council |
| WE | watch error |
| WGS | World Geodetic System |
| Wk | wreck |
| WMO | World Meteorological Organization |
| WWNWS | World Wide Navigational Warning Service |
| WT | watch time |

## X – Y – Z

| X | parallactic angle |
| XMTR | transmitter |
| y. | yellow |
| yd(s). | yard(s) |
| yr(s). | year(s) |
| z | zenith distance |
| Z | azimuth angle; zenith |
| ZD | zone description |
| Z Diff. | azimuth |
| Znpgc | azimuth per gyrocompass |