N2 Nitrogen NAV Navigation NM Nautical Miles NOM Nominal NXX Noun XX O2 Oxygen OBS Observation O/F Oxidizer to Fuel Ratio OGA Outer Gimbal Angle OMNI Omnidirectional Antenna OPS Oxygen Purge System ORB Orbital ORDEAL Orbit Rate Display Earth and Lunar ORIENT Orientation OVHD Overhead P Pitch or Program PAD Voice Update PCM Pulse Code Modulation PC Plane Change PDI Powered Descent Initiation PGA Pressure Garment Assembly PGNCS Primary Guidance Navigation Control Section PIPA Pulse Integrating Pendulous Accelerometer PLSS Personal Life Support Systems PM Phase Modulated POL Polarity or Polarizing PRE Pretoria, South Africa PREF Preferred PREP Preparation PRESS Pressure PRIM Primary PROP Proportional PSE Passive Seismic Experiment PT Point PU Propellant Utilization PUGS Propellant Utilization and Gaging System PTC Passive Thermal Control PWR Power PXX Program XX Qty Quantity R Roll or Range R&B Red & Blue RAD Radiator RCDR Recorder RCS Reaction Control System RCU Remote Control Unit RCV Receiver RED USNS Redstone REFSMMAT Reference Stable Member Matrix REG Regulator REQD Required RH Right-hand RING Ringsite RLS Radius of Landing Site RNDZ Rendezvous RR Rendezvous Radar RSI Roll Stability Indicator RT Real Time RTC Real Time Command RXX Routine XX SA Shaft Angle S/C Spacecraft SCE Signal Conditioning Equipment SCS Stabilization Control System SCT Scanning Telescope vi