Appendix I-Glossary-Cont.

IDA— Input data acknowledge IDR— Input data request IEEE— Institute of Electrical and Electronics Engineer I/O— input/output ISO— International Standards Organization JTIDS— Joint Tactical Information Distribution System JU— JTIDS unit kHz— Kilohertz lf— Low frequency LAN— Local area network log— Logarithm LMS— Link monitor system LSB— Lower sideband mf— Medium frequency MHZ— Megahertz MODEM— MOdulator Demodulator MCM— Monitor control message MRM— Monitor reply message MUF— Maximum useable frequency NATO— National Alliance Treaty Organization NIC— Network interface card NICP— Network interface computer program NCS— Net control station NTR— Network time reference ODR— Output data request OSI— Open system interconnection AI-2 POFA— Programmed operational and fictional appraisal PIU— Power interface unit PU— Participating unit R/T— Receiver/transmitter group RGB— Red, green, and blue RCV— Receive SDLC— Synchronous data link control SDU— Secure data unit SNR— Signal-to-noise ratio SGS— Shipboard Gridlock System shf— Superhigh frequency SINS— Ship’s Inertial Navigation System TADIL— Tactical Data Information Link TDM— Time-division multiplexing TDMA— Time-division multiple access TQ— Track quality uhf— Ultra-high frequency USB— Upper sideband µsec— Microsecond UTM— Universal test message vhf— Very high frequency vlf— Very low frequency XMT— Transmit