1,2,Provide a frame alignment pattern 提供帧定位类型 A1 = 11110110 A2 = 00101000Format: 3N 格式： 3N,Framing Bytes A1, A2 帧定位字节,3,Transmits a fixed pattern repetitively 反复传送一个固定类型Used by the section receiver to verify its continued connection to the intended transmitter 用于段接收机向发送机确认它 的继续连接性Format: 1 格式： 1,Regenerator Section Trace J0 中继段跟踪,4,Provides an 8-bit wide bit- interleaved even parity check for error performance monitoring at the regenerator section level 在中继段级别上，为误码性能监测 提供8个比特位的偶校验The parity check is computed for all bytes of the previous STM-N frame after scrambling 对扰码后的前个STM-N所有字节 进行奇偶校验The computed value is placed in this byte before scrambling 在扰码前将检验结果存于该字节Format: 1 格式： 1,8-bit Parity Check B1 8比特奇偶校验,5,Provide a local orderwire channel for voice communication 为语音通信提供本地公务信道 E1 may be accessed by regenerators 中继器可以访问E1 E2 may be accessed by multiplexers 复用器可以访问E2 Format: 1 格式： 1,Orderwire Channels E1, E2 公务信道,6,Allocated for users purposes 为用户目的分配的信道Terminated at all regenerator section-level equipment 在所有的中继段级别设备终止Format: 1 格式： 1,User Channel F1 用户信道,7,Provide a message-based data communications channel, including administration, monitor, alarm and maintenance functions 提供包括管理、监测、告警和维护等功能的信息数据通信信道 D1-D3 define a 192 kbit/s channel in the RSOH 定义D1-D3为192kbit/s的信道 D4-D12 define a 576 kbit/s channel in the MSOH 定义D4-D12为576kbit/s的信道 Format: 1 格式： 1,Datacom Channel (DCC) D1-D3, D4-D12 数据通信信道,8,Provide indications and flags regarding the frame contents 提供帧内容的指示和标记 Define the start position of the VC-4 within the STM-1 frame 定义VC-4在STM-1帧内的起始位置 Provide a method of the VC-4 floating within the AU-4 frame提供VC-4在AU-4帧内浮动的方法 Provide an indication of AU-4 concatenation 提供AU-4串联指示 Format: 3N 格式： 3N,AU Pointer Bytes H1-H3 管理单元指针字节,9,Link Between Section Overhead and VC 段开销与虚容器的联系,10,AU-4 Pointer Adjustment Operation - Positive Justification AU-4 指针调节 - 正向调节,11,AU-4 Pointer Adjustment Operation - Negative Justification AU-4 指针调节 - 逆向调节,12,Include a 24-bit wide bit-interleaved even parity check, for error performance monitoring at the multiplexer section level 在复用段级别上，为误码性能监测提供24个比特位的偶校验The check is computed for all bytes of the previous STM-N frame, except those located in the RSOH 对前一个STM-N除RSOH外所有字节进行检验Format: 3N 格式： 3N,24-bit Parity Check B2 24比特奇偶校验,13,Provides MPS signalling between multiplexer section terminating equipment 在复用段设备之间，提供MPS信令Format: 1 格式： 1,Multiplexer Protection Switching (MPS) K1 复用器保护倒换,14,Used to return an indication to the transmit end that the received end has detected an incoming section defect or is receiving AIS 接收端在收到AIS或当接收段故障 时向发送端反馈的指示Format: 1 格式： 1,Remote Defect Indication (RDI) K2 远端故障指示,15,Indicates the type of clock source used to time the transmitted signal 指示传送信号定时的时钟源种类 The indications are one of the four synchronization levels agreed to by the ITU-T, or patterns to indicate that the quality is unknown or should not be used 包括ITU-T协议所规定的4个同步 级别中的一种，或指示质量不知 道以及不可用 Format: 1 格式： 1,Quality of Synchronization S1 同步质量,16,Used to send error performance information from multiplexer section receiving equipment to the originating equipment 复用段接收机向发射机反馈的 误码性能信息Conveys the count of interleaved bit blocks detected in error by the B2 byte 传达B2检测出的错误比特块数量Format: 1 格式： 1,Remote Error Indication (REI) M1 远端错误指示,17,Provides a unique message set up for each path in the SDH network 为SDH网络中的每个通道提供 唯一性信息Supports continuity testing between any location on a transmission path 支持传输通道任意端点间的连续性测试Format: 1N 格式： 1N,Path Trace Byte J1 通道跟踪,18,Includes an 8-bit wide bit-interleaved parity check that provides error performance monitoring at the VC-4 level 在VC-4级别上，为误码性能监测 提供8个比特位的奇偶校验The parity check is computed for all bytes of the previous VC-4 before scrambling 对扰码前的前个VC-4进行奇偶校验The computed value is placed in this byte before scrambling 在扰码前将检验结果存于该字节,8-bit Parity Check B3 8比特奇偶校验,19,Provides an indication of the payload construction 提供净负荷结构指示Indicates the type of payloads which are mapped into the virtual container 说明映射于虚容器中净负荷的种类,