Acronyms:
P - S
P-NNI - Private Network to Network Interface
PAD - Packet Assembler and Disassembler
PBX - Private Branch eXchange
PC - Priority Control
PC - Protocol Control
PCM - Pulse Code Modulation
PCO - Point of Control and Observation
PCR - Peak Cell Rate
PCR - Program Clock Reference
PCVS - Point to Point Switched Virtual Connections
PD - Packetization Delay
PDH - Plesiochronous Digital Hierarchy
PDU - Packet Data Unit
PDU - Protocol Data Unit
PHY - Physical Layer of the OSI model
PHY - Physical Layer
PICS - Protocol Implementation Conformance Statement
PID - Protocol Identifier Governing Connection Types
PIXIT - Protocol Implementation eXtra Information for Testing
PL - Physical Layer
PLL - Phase Locked Loop
PLPC - Physical Layer Convergence Protocol
PM - Physical Medium
PMD - Physical Layer Dependent sub-layer
POH - Path Overhead
POI - Path Overhead Indicator
PT - Payload Type
PTI - Payload Type Identifier
PVC - Permanent Virtual Circuit
PVCC - Permanent Virtual Channel Connection
PVPC - Permanent Virtual Path Connection
QD - Queuing Delay
QOS/QoS - Quality of Service
QPSX - Queue Packet and Synchronous Circuit Exchange
RAI - Remote Alarm Indication
RBOC - Regional Bell Operating Company
RC - Routing Control
RD - Route Descriptor
RDF - Rate Decrease Factor
RDI - Remote Defect Identification
RDI - Remote Defect Indication
REL - Release Message
RFC - Request For Comment (Document Series)
RFI - Radio Frequency Interference
RI - Routing Information
RII - Routing Information Indicator
RIP - Routing Information Protocol
RISC - Reduced Instruction Set Computing
RLC - Release Complete
RM - Resource Management
ROLC - Routing Over Large Clouds
RSVP (protocol) - Resource Reservation Protocol
RT - Routing Type
RTS - Residual Time Stamp
SA - Source MAC address
SA - Source Address
SAAL - Signaling ATM Adaptation Layer
SAP - Service Access Point
SAR - Segmentation and Reassembly
SCCP - Signaling Connection and Control Part
SCP - Service Control Point
SCR - Sustainable Cell Rate
SDH - Synchronous Digital Hierarchy
SDU - Service Data Unit
SE - Switching Element
SEAL - Simple and Efficient Adaptation Layer
SF - Switching Fabric
SGM - Segmentation Message
SID - Signaling Identifier
SIPP - SMDS Interface Protocol
SIR - Sustained Information Rate
SMC - Sleep Mode Connection
SMDS - Switched Multi-megabit Data Services
SMF - Single Mode Fiber
SN - Sequence Number
SNA - Systems Network Architecture
SNAP - Sub Network Access Protocol
SNMP - Simple Network Management Protocol
SOH - Section Overhead
SONET - Synchronous Optical Network
SPID - Service Protocol Identifier
SPTS - Single Program Transport Stream
SR - Source Routing (Bridging)
SRF - Specifically Routed Frame
SRT - Source Routing Transparent
SRTS - Synchronous Residual Time Stamp
SSCF - Service Specific Coordination Function
SSCOP - Service Specific Connection Oriented Protocol
SSCS - Service Specific Convergence Sublayer
ST - Segment Type
STE - Spanning Tree Explorer
STM - Synchronous Transfer Mode
STM1 - Synchronous Transport Mode 1 -- 155mbits/sec
STP - Signaling Transfer Point
STP - Shielded Twisted Pair cable
STS - Synchronous Time Stamps
STS-3c - Synchronous Transport System-Level 3 concatenated
SUT - System Under Test
SVC - Switched Virtual Circuit
SVCI - Switched Virtual Circuit Identifier
SVP - Switched Virtual Path
SWG - Sub-Working Group