37SSIM-R2-02/SSIM-R8-02 HSTR SmartStack Interface Modules Installation and User GuideAppendix A. AbbreviationsAC Access ControlARE All-Routes ExplorerATM Asynchronous Transfer ModeBRF Bridge Relay FunctionCFI Canonical Format IndicatorCRC Cyclic Redundancy CheckCRF Concentrator Relay FunctionDA Destination AddressDSAP Destination SAPDTR Dedicated Token RingECO Engineering Check OrderFC Frame ControlFCS Frame Check SequenceFDX Full DuplexHDX Half DuplexHSTR High-Speed Token RingIP Internet ProtocolLAN Local Area NetworkLED Light Emitting DiodeLLC Logical Link ControlMAC Media Access ControlMbps MegaBit Per SecondMMF Multi Mode FiberMTU Maximum Transmission UnitNSR Non-Source RoutedNVRAM Non-Volatile RAMRAM Random Access Memory