Acronym,Meaning A/S,Anti-Spoofing AAIM,Airborne Autonomous Integrity Monitoring ABAS,Aircraft Based Augmentation Systems ACAC,Arab Civil Aviation Commission ACF,Auto-Correlation Function ADAS,Advanced Driving Assistance Systems ADC,Analog to Digital Converter ADS-B,Automatic Dependent Surveillance-Broadcast AEP,Architecture Evolution Plan AF,U.S. Air Force AFCAC,African Civil Aviation Commission AFI,Africa-Indian Ocean AGC,Automatic Gain Control AHRS,Attitude and Heading Reference Systems AIS,Automatic Identification System AIV,Assembly AL,Alert Limit AltBOC,Alternative BOC AM,Amplitude Modulation AMCS,Alternate Master Control Station ANSP,Air Navigation Service Provider ANTEX,ANtenna EXchange format AOA,Airport Operators Association AOA,Angle Of Arrival AOAD/M,T Allen Osborne Associates Dorne Margolin Model T AOC,Advanced Operational Capability AOCS,Attitude and Orbit Control Subsystem AOR,Atlantic Ocean Region AP,Access Point AP,Application Protocol APC,Antenna Phase Centre APEC,Asia Pacific Economic Cooperation API,Application Programming Interface APIRG,AFI Planning and Implementation Regional Group APPS,Automatic Precise Positioning Service APV,Approach oPerations with Vertical guidance APVI,Approach oPerations with Vertical guidance I APVII,Approach oPerations with Vertical guidance II AR,Axial Ratio ARAIM,Advanced RAIM ARNS,Aeronautical Radio Navigation Service ARP,Antenna Reference Point ARPA,Automatic Radar Plotting Aids AS,Anti-Spoofing ASBC,Advanced Space Business Corporation ASECNA,from french: Agence pour la Securite de la Navigation Aerienne en Afrique et … Madagascar ASICs,Applications Secific Integrated Circuit ASN.1,Abstract Syntax Notation 1 ASQF,Application Specific Qualification Facility ASZ,Autocorrelation Side-lobe Zero ATC,Air Traffic Control ATM,Automated Teller Machine ATM,Air Traffic Management ATV,Automated Transfer Vehicle AUC,African Union Commission AWGN,Additive White Gaussian Noise AWOP,All Weather Operations Panel BC,Before Christ BCS,Binary Coded Symbols BDT,BeiDou Time BI,Behavioral Interventions BIE,Bureau International de l'Heure BIH,From French: Bureau International de l'Heure BIPM,Bureau International des Poids et Mesures BLUE,Best Linear Unbiased Minimum-Variance Estimator BM,Benchmark BMCS,Backup Master Control Station BOC,Binary Offset Carrier BPSK,Binary Shift Phase Keying BRS,Baricentric Reference System C/A,Coarse/Acquisition C/NAV,Commercial Navigation Message CAASD,Center for Advanced Aviation System Development (MITRE) CAES,Computer Aided Earthmoving System CAN,Controller Area Network CAR,Caribbean and South American region CARERI,Chinese Aeronautical Radio Electronics Research Institute CASM,Coherent Adaptive Sub-Carrier Modulation CBCS,Composite Binary Coded Symbols CBOC,Composite BOC CCF,Central Control Facility CCZ,Congestion Charge Zone CDCM,Coastal Defense Cruise Missile CDDIS,Crustal Dynamics Data Information System CDDS,Commercial Data Distribution Service CDMA,Code Division Multiple Access CDTI,Cockpit Display of Traffic Information CEP,Conventional Ephemeris Pole CEP,Circular Error Probable CF,Compact Flash CFSP,Common Foreign and Security Policy CGCS2000,China Geodetic Coordinate System 2000 CGSIC,Civil GPS Service Interface Committee CHA,Channel of High Accuracy CHAMP,CHAllenging Minisatellite Payload CHARS,Customer Hierarchy And Reporting System CIO,Conventional International Origin CIP,Celestial Intermediate Pole CIR,Cascading Integer Resolution CIS,Conventional Inertial System CL,Civil Long CM,Civil Moderate CMCF,Central Monitoring and Control Facility CMR,Compact Measurement Record CMSA,Cruise Missile Support Activity CNAV,Civil NAVigation message CNS,Communication Navigation Surveillance CNSS,Compass Navigation Satellite System COCESNA,Corporacion Centroamerica de Servicios de Navegacion Aerea CODE,Centre for Orbit Determination in Europe CONUS,CONtinental United States CORS,Continuously Operating Reference Stations COSMIC,Constellation Observing System for Meteorology CP,Circular Polarization CPF,Central Processing Facility CPFPS,Central Processing Facility Processing Set CPN,Coloured Petri Nets CPU,Central Processing Unit CR,Council Resolution CRC,Cyclic Redundancy Check CRF,Celestial Reference Frame CRLB,Cramer Rao Lower Bound CRS,Conventional Celestial Reference System CRT,Cathode Ray Tube CS,Commercial Service CSA,Channel of Standard Accuracy CSIM,Constellation Simulator CSK,Code Shift Keying CSRS,Canadian Spatial Reference System CTP,Conventional Terrestrial Pole CTS,Conventional Terrestrial System CW,Continuous Wave CWAAS,Canadian WAAS DAB,Digital Audio Broadcasting DAC,Digital-to-Analog Converters DASS,Distress Alerting Satellite System DCB,Differential Code Biases DDMA,Doppler Division Multiple Access DEOS,Delft Institute of Earth Observation and Space Systems DF,Dual Frequency DGNSS,Differential GNSS DGPS,Differential GPS DGRS,DGPS Reference Station DH,Decision Height DLL,Delay Lock Loop DME,Distance Measuring Equipment DoD,US Department of Defense DOP,Dilution Of Precision DOT,Department Of Transportation DoY,Day-of-Year DP,Dot Product DSCS,Defense Satellite Communications System DSNS,Differential Satellite Navigation Systems DSP,Digital Signal Processor DSPN,Direct Sequence Pseudo Noise DSRC,Dedicated Short-Range Communications DSSS,Direct Sequence Spread Spectrum DVP,Development and Verification Platform EASA,European Aviation Safety Agency EC,European Commission ECA,Error Characterization Approach ECAC,European Civil Aviation Conference ECAM,Electronic Centralised Aircraft Monitor ECEF,Earth Centred Earth Fixed ECI,Earth Centred Inertial ECMWF,European Centre for Medium-Range Weather Forecasts EDAS,EGNOS Data Access System EDS,EGNOS Data Server EEGS,EGNOS Extension to Eastern Europe EETS,European Electronic Tolling Service EFC,Electronic Fee Collection EFIS,Electronic Flight Instrument System EGNOS,European Geostationary Navigation Overlay System EICAS,Engine Indications and Crew Alerting System EIRP,Effective Isotropic Radiated Power E-L,Early-Late ELT,Emergency Location Terminal EMLP,Early Minus Late Power EMP,Electro-Magnetic Pulse EMR,Energy Mines and Resources EMT,Effective Monitor Threshold ENC,European Navigation Conference ENT,EGNOS Network Time ENU,East North Up EOL,End-Of-Life EOP,Earth Orientation Parameters EPFS,Electronic Position Fixing System EPIRB,Emergency Position Indicating Radio Beacons EPPP,Enhanced Precise Point Positioning ERIS,External Regional Integrity Services ERP,Earth Rotation Parameters ERTMS,European Rail Traffic Management System ESA,European Space Agency ESDP,European Security and Defence Policy ESOC,European Space Operations Centre ESSP,European Satellite Service Provider ESTB,EGNOS Test Bed ET,Ephemeris Time ETA,Estimated Time of Arrival ETC,Electronic Tolling Collection ETCS,European Train Control System ETML,European Traffic Management Layer ETSO,European Technical Standard Order EU,European Union EuCAP,European Conference on Antennas and Propagation EWAN,EGNOS Wide Area Network F/NAV,Freely accessible Navigation Message FAA,Federal Aviation Administration FAS,Final Approach Segments FDE,Fault Detection and Exclusion FDF,Flight Dynamics Facility FDMA,Frequency Division Multiple Access FEC,Forward Error Correction FH,Faded-Harmonics FIR,Flight Information Region FIR,Finite Impulse Response FKP,From German: Flaechen Korrektur Parameter FLL,Frequency Lock Loop FM,Frequency Modulation FMS,Flight Management System FOC,Full Operational Capability FOP,Final Operational Phase FPGA,Field Programmable Gate Array F-PPP,Fast Precise Point Positioning FTP,File Transfer Protocol G/NAV,Governmental Navigation Message GA,Ground Antennas GACF,Ground Assets Control Facility GADEROS,Galileo Demonstrator for Railway Operation System gAGE,Research group of Astronomy and GEomatics GAST,Greenwich Apparent Sidereal Time GBAS,Ground-Based Augmentation System GCC,Ground Control Centres GCS,Ground Control Segment GDOP,Geometric Dilution Of Precision GEAS,GNSS Evolutionary Architecture Study GEO,Geostationary Orbit GESS,Galileo Experimental Sensor Stations GGSP,Galileo Geodetic Service Provider GIC,GNSS/Ground Integrity Channel GIM,Global Ionospheric Maps GIOVE,Galileo In-Orbit Validation Element GIS,Geographic Information System GIT,GNSS Implementation Team GIVD,Grid Ionospheric Vertical Delay GIVE,Grid Ionospheric Vertical Error GIVEI,GIVE Indicators GJU,Galileo Joint Undertaking GLA,General Lighthouse Authorities GLONASS,GLObal NAvigation Satellite System GLONASST,GLONASS Time GLP,Good Laboratory Practice GLS,GNSS Landing System GMDSS,Global Maritime Distress and Safety System GMS,Ground Mission Segment GMSK,Gaussian Minimum Shift Keying GMST,Greenwich Mean Sidereal Time GMT,Greenwich Mean Time GNS,Global Navigation System GNSS,Global Navigation Satellite System GNSSP,GNSS Panel GOC,Galileo Operating Company GPRS,General Packet Radio Service GPS,Global Positioning System GPS/MET,Global Positioning System/Meteorology GPSOC,GPS Operations Center GPST,GPS Time GPSW,GPS Wing GRACE,Gravity Recovery And Climate Experiment GRAPHIC,Group and Phase Ionospheric Calibration GRAS,Ground-based Regional Augmentation System GRS,Geodetic Reference System GRSP,Galileo Geodetic Reference Service Provider GSA,European GNSS Agency GSLV,Geosynchronous Satellite Launch Vehicle GSM,Global System for Mobile communication GSO,Geostationary Satellites Orbit GSS,Galileo Sensor Stations GST,Galileo System Time GTRF,Galileo Terrestrial Reference Frame GUS,Ground Uplink Stations HAL,Horizontal Alert Limit HD,Hydrostatic Delay HD,Hard Disk HDOP,Horizontal Dilution Of Precision HEO,Highly Elliptical Orbit HF,High Frequency HIS,High Integrity Service HMI,Hazardous Misleading Information HP,High Precision HPA,High Power Amplifier HPE,Horizontal Position Error HPL,Horizontal Protection Level HPPS,High Precision Positioning Service HPS,High Precision Service HTML,Hyper Text Markup Language I/NAV,Integrity Navigation Message IAEA,International Atomic Energy Agency IAG,International Association of Geodesy IAS,Institut Aero Spatial IAU,International Astronomical Union IBPL,Isotropy Based Protection Level IBS,Integrated Bridge Systems IC,Integrated Chips ICAO,International Civil Aviation Organization ICC,Institut Cartografic de Catalunya ICD,Interface Control Document ICG,International Committee on Global Navigation Satellite Systems ICR,Isotropic Confidence Ratio ICRF,International Celestial Reference Frame ICRS,International Celestial Reference System ICS,Internal Communication Subsystem IDF,Ionospheric Disturbance Flag IEP,Initial Experimental Phase IERS,International Earth Rotation and Reference Systems Service IF,Intermediate Frequencies IGEX,International GLONASS EXperiment IGP,Ionospheric Grid Point IGS,International GNSS Service IGSO,Inclined Geo-Synchronous Orbit ILRS,IRNSS Laser Ranging Station ILS,Instrument Landing Systems IM,Inter Modulation IMO,International Maritime Organization IMU,Inertial Measurement Unit INC,IRNSS Navigation Centre INLUS,Indian Land Uplink Station INMCC,Indian Master Control Center INRES,Indian REference Stations INS,Inertial Navigation System IOC,Initial Operational Capability IOD,Issues of Data IODC,Issue of Data Clock IODE,Issue Of Data Ephemeris IODF,Issue Of Data Fast Corrections IODI,Issue of Data IGP Mask IODN,Issue of Data Navigation IODP,Issue Of Data PRN mask IODS,Issue of Data Service Message ION,Institute Of Navigation IONEX,IONosphere map EXchange format ION-NTM,ION National Technical Meeting IOR-W,Indian Ocean Region West IOT,In-Orbit Test IOV,In-Orbit Validation IP,Internet Protocol IPF,Integrity Processing Facility IPP,Ionospheric Pierce Point IRCDR,IRNSS CDMA Ranging Stations IRDCN,IRNSS Data Communication Network IRIMS,IRNSS Range and Integrity Monitoring Stations IRN,Information Request Notice IRNSS,Indian Regional Navigational Satellite System IRNWT,IRNSS Timing Centre IRTTC,IRNSS TTC and Uplinking Stations ISI,Inter Symbol Interference ISM,Integrity Support Message ISRO,Indian Space Research Organization ISS,International Space Station ITR,International Terrestrial Reference ITRF,International Terrestrial Reference Frame ITRS,International Terrestrial Reference System ITU,International Telecommunications Union ITU-R,International Telecommunications Union Radiocommunication Sector IWG,Interoperability Working Group JAXA,Japan Aerospace Exploration Agency JD,Julian Day JLOC,Jammer Location JMA,Japan Meteorological Agency JPL,Jet Propulsion Laboratory KH,Kelvin-Helmholtz KMF,Key Management Facility L2CL,L2 Civil Long L2CM,L2 Civil Moderate LAAS,Local Area Augmentation System LAST,Local Apparent Sidereal Time LBS,Location Based Services LCA,Liability Critical Applications LCD,Liquid Crystal Display LEO,Low Earth Orbit LEOP,Launch Early OPerations LEX,Michibiki experimental signal LFSR,Linear Feedback Shift Registers LHCP,Left Hand Circular Polarization LM,Local Mean LMST,Local Mean Sidereal Time LNA,Low Noise Amplifier LNAV,Lateral Navigation LO,Local Oscillator LOC,Linear Offset Carrier LOS,Line-Of-Sight LP,Localizer Performance LPV,Localizer Performance with Vertical guidance LRIT,Long Range Identification and Tracking LT,Long Term LVP,Low Visibility Procedures MASPS,Minimum Aviation System Performance Standards MBOC,The Multiplexed Binary Offset Carrier MCC,Mission Control Centers MCS,Master Control Station MCS,Multilevel Coded Spreading Symbols MEAG,Mission Evolution Advisory Group MEDLL,Multipath Estimating Delay Lock Loop MEH,Marine Electronic Highway MEO,Medium Earth Orbit MEOSAR,Medium Earth Orbit Search And Rescue METIS,Mediterranean Introduction of GNSS Services MGF,Message Generation Facility MHSS,Multiple Hypothesis Solution Separation MI,Misleading Information MJD,Modified Julian Day MLS,Microwave Landing System MLU,MRS Land User service MM,Monument Marker MMI,Man Machine Interface MMSSS,Multi-Mode Spread-Spectrum Sub-carrier Modulation MNAV,Military NAVigation Message MOB,Man Overboard MODIP,MOdified DIP latitude MOPS,Minimum Operational Performance Specification MPR,MultiPath Ratio MPSK,Multiple Phase Shift Keying MRA,Measurement Rejection Approach MRS,Multi-Constellation Regional System MS,Monitor Stations MSAS,MTSAT Satellite Augmentation System MSC,Mobile Satellite Communications MSD,Minimum Set of Data MSE,Mean-Square Error MSF,Mission Support Facility MSI,Misleading Signal-in-Space Information MSK,Minimum Shift Keying MSTID,Medium Scale Traveling Ionospheric Disturbances MT,Military Tracking MT,Message Type MT0,Message Type 0 MT1,Message Type 1 MT2,Message Type 2 MT3,Message Type 3 MT4,Message Type 4 MT5,Message Type 5 MTPF,Maintenance and Training Platform MTSAT,Multifunctional Transport Satellite MUCF,Mission Uplink Control Facility NAD83,North American Datum of 1983 NANUs,Notice Advisory to Navstar Users NAPEOS,Navigation Package for Earth Observation Satellites NAS,National Airspace System NASA,National Aeronautics and Space Administration NAV,Navigation Message NAVCEN,NAVigation CENter NCA,Non-Critical applications NCO,Numerical Control Oscillators NDB,Non-Directional Beacon NDGPS,Nationwide Differential Global Positioning System NELP,Non-coherent Early minus Late Power NEU,North-East-Up NGA,National Geospatial-Intelligency Agency NIST,National Institute of Standards and Technology NLES,Navigation Land Earth Stations NLOS,Non Line Of Sight NMCS,New Master Control Station NMEA,National Marine Electronics Association NOCC,National Operations Control Center NOTAM,NOTice to AirMen NPA,Non-Precision Approach NPV,Non Precision Approach with vertical guidance NRTK,Network RTK NRZ,Non-Return to Zero NSE,Navigation System Error NSP,Navigation System Panel NSU,Navigation Signal generator Unit NSV,Near Space Vehicle NTRIP,Networked Transport of RTCM via Internet Protocol OA,Operational Advisories OBD,On-Board diagnostics OBU,On Board Unit OCC,Operational Control Centers OCS,Operational Control System OCX,Operational Control Segment OD&TS,Orbit Determination and Time Synchronisation ODTS,Orbit Determination and Time Synchronisation OEM,Original Equipment Manufacturer OLAF,from French: Office de Lutte Anti-Fraude ONCE,Spanish organisation for the blind OPF,Operations Preparation Facility OQPSK,Offset QPSK ORMS,Orbiter and Radio Metric Systems OS,Open Service OS,Operative System OSD,Open Signal Data OSP,Open Signal Pilot OSPF,Orbit determination and Synchronization Processing Facility OTF,On-The-Fly PA,Precision Approach PACF,Performance Assessment and Checkout Facility PANS,Procedures for Air Navigation Services PAYD,Pay-As-You-Drive PBN,Performance-Based Navigation PCV,Phase Centre Variations PDA,Personal Digital Assistant PDF,Portable Document Format PDM,Position Domain Monitoring PDOP,Position Dilution Of Precision PE,Protection Error PFD,Primary Flight Display PL,Protection Level PLANS,Position Location and Navigation Symposium PLL,Phase Lock Loop PM,Phase Modulation PND,Portable Navigation Devices PNG,Portable Network Graphics PNT,Positioning POD,Precise Orbit Determination POI,Point Of Interest PPP,Precise Point Positioning PPS,Precise Point Service PR,Pseudo Random PRN,Pseudo-Random Noise PRS,Public Regulated Service PRTODTS,Precise Real Time Orbit Determination and Time Synchronization PS,Precision Service PSD,Power Spectral Density PSK,Phase-Shift Keying PSTD,Pseudospectral Time-Domain PTC,Positive Train Control PTF,Precision Timing Facility PTP,Point-To-Point PVT,Position PZ-90,Parametry Zemli 1990 (Parameters of the Earth 1990) QOS,Quality Of Service QPSK,Quadrature Phase-Shift Keying QPSM,Quadrature Product Sub-carrier Modulation QZSS,Quasi-Zenith Satellite System RAAN,Right Ascension of the Ascending Node RAIM,Receiver Autonomous Integrity Monitoring RC,Rased Cosine RCF,Raised Cosine Filter RDS,Radio Data System RDSS,Radio Determination Satellite Service RECs,Regional Economic Communities RF,Radio Frequency RFC,Radio Frequency Compatibility RFI,Radio Frequency Interference RFID,Radio-Frequency Identification RHCP,Right Hand Circular Polarization RICS,Royal Institution of Chartered Surveyors RIMS,Ranging Integrity Monitoring Stations RINEX,Receiver INdependent EXchange format RK4,4th order Runge-Kutta RMS,Root Mean Square RNAV,aRea NAVigation RNP,Required Navigation Performance RNSS,Radionavigation Satellite System RRAIM,Relative RAIM RRC,Range Rate Corrections RRC,Root Raised Cosine RSA,Russian Space Agency RSIM,Reference Stations and Integrity Monitors RSN,Reference Stations Network RTCM,Radio Technical Commission for Maritime Services RTK,Real-Time Kinematics RUC,Road User Charging RX,Receiver S/A,Selective Availability SA,Select Availability SACCSA,From Spanish: Soluci¢n de Aumentaci¢n para el Caribe SAIF,Submeter-class Augmentation with Integrity Function SAM,South America Region SAR,Search and Rescue SARPs,Standard and Recommended Practices SBAS,Satellite-Based Augmentation System SBCS,Sinusoidal Binary Coded Symbols SCA,Safety Critical Applications SCC,System Control Centre SCC,Spacecraft Control Centre SCCF,Spacecraft and Constellation Control Facility SCPF,Spacecraft and Constellation Planning Facility SDA,System Design Approval SDCM,System of Differentional Correction and Monitoring SDD,Service Definition Document SDR,Software Defined Radio SEP,Spherical Error Probable SF,Single Frequency SGLS,Space Ground Link Subsystem SI,International System of Physical Units SINEX,Solution (Software/technique) INdependent EXchange format SIS,Signal In Space SISA,Signal-in-Space Accuracy SISE,SIS Error SISMA,SIS Monitoring Accuracy SLR,Satellite Laser Ranging Station SMCS,Sinusoidal Multilevel Coded Symbol SMS,Short Message Service SNAS,Satellite Navigation Augmentation System SNIR,Signal to Noise plus Interference Ratio SNR,Signal to Noise Ratio SNT,SBAS Network Time SOC,Sinusoidal Binary Offset Carrier SoL,Safety-of-Life SOLAS,Safety of Life at Sea SOTDMA,Self-Organizing Time Division Multiple Access SP,Service Provider SP3,Standard Product #3 SPAC,Satellite Positioning Research and Application Center SPD,Slant Path Delay SPEED,Support Platform for EGNOS Evolutions and Demonstrations SPF,Service Product Facility SPP,Standard Point Positioning SPS,Standard Positioning Service SQM,Signal Quality Monitoring SRD,System Requirement Document SRIF,Square-Root Information Filtering SRRC,Square-Root Raised Cosine SS,Spread Spectrum SSC,Spectral Separation Coefficient SSEG,Space Segment SSTL,Surrey Satellite Technology Ltd. ST,Short Term STC,aircraft Supplemental Type Certificates STEC,Slant Total Electron Content STF,Signal Task Force SU,Soviet Union SUPPs,regional SUPplementary Procedures SV,Space Vehicle SVN,Space Vehicle Number SW,Synchronization Words SW,Software TACAN,TACtical Air Navigation TAI,From French: Temps Atomique International TBD,see TCB TCA,Terminal Control Area TCAR,Three-Carrier Ambiguity Resolution TCAS,Traffic Collision Avoidance System TCB,from French: Temps Coordonnee Barycentrique TCG,from French: Temps Coordonnee Geocentrique TDARDS,Truth Data Acquisition TDB,from French: Temps Dinamique Barycentrique TDOP,Time Dilution Of Precision TDS,Technology Demonstration System TDT,Terrestrial Dynamic Time TEC,Total Electron Content TECU,Total Electron Content Unit TGD,Total Group Delay TLM,TeLeMetry TLS,Target Level of Safety TMBOC,Time-Multiplexed BOC TMR,Triple Modular Redundancy TOW,Time Of Week TRF,Terrestrial Reference Frame TRS,Conventional Terrestrial Reference System TS,Time Synchronisation TSO,Technical Standard Order TT,Terrestrial Time TT&C,Telemetry TTA,Time-To-Alert TTC,Telemetry TTFF,Time To First Fix TUS,Test User Segment TV,Television TX,Transmitter U.S.,United States UAV,Unmanned Aerial Vehicle UCAR,University Corporation of Atmospheric Research UDRE,User Differential Range Error UDREI,UDRE Indicator UEN,Up-East-North UERE,User Equivalent Range Error UIRE,User Ionospheric Range Error UK,United Kingdom ULS,Mission Uplink Stations UMTS,Universal Mobile Telecommunications System UNB,University of New Brunswick UNE,Up North East UNECA,United Nations Economic Commission for Africa UNISPACE,United Nations Conference on the Exploration and Peaceful Uses of Outer Space UPC,Technical University of Catalonia URA,User Range Accuracy URE,User Range Error US,United States USA,United States of America USB,Universal Serial Bus USCG,U.S. Coast Guard USNDS,US Nuclear Detonation (NuDet) Detection System USNO,United States Naval Observatory UT,Universal Time UT0,Universal Time 0 UT1,Universal Time 1 UT2,Universal Time 2 UTC,Universal Time Coordinated UV,Ultra Violet VAL,Vertical Alert Limit VDB,VHF Data Broadcast VDLL,Vector DLL VDOP,Vertical Dilution Of Precision VE,Very Early VHF,Very High Frequency VL,Very Late VLBI,Very Long Baseline Interferometry VNAV,Vertical Navigation VOR,VHF Omnidirectional Range VPE,Vertical Position Error VPL,Vertical Protection Level VRS,Virtual Reference Station VTS,Vessel Traffic Service WAAS,Wide Area Augmentation System WAD,Wide Area Differential WADGPS,Wide Area Differential GPS WAGE,Wide Area GPS Enhancements WAN,Wide Area Network WAP,Wireless Application Protocol WARTK,Wide Area Real-Time Kinematics WARTK-EGAL,Wide Area Real-Time Kinematics based on EGNOS and Galileo WG,World Geodetic WG,Working Group WGS,World Geodetic System WGS84,World Geodetic System 84 WLS,Weighted Least Square WMS,WAAS Master Station WRC,World Radio Conference WRS,Wide-area Reference Stations XPE,Vertical/ Horizontal Protection Error XPL,Vertical/ Horizontal Protection Level ZHD,Zenith Hydrostatic Delay ZPD,Zenith Path Delay ZTD,Zenith Tropospheric Delay ZWD,Zenith Wet Delay