ISO/IEC 11518的这一部分规定了一种物理级、点对点、全双工、链路接口，用于以每方向6400 Mbit/s的速度，跨长达1 km的距离，可靠地传输用户数据。规定了距离不超过40米的平行铜电缆接口。提供与单独的远距离光学接口的连接。小型固定大小的微包为小型传输提供了高效、低延迟的结构，并为大型传输提供了组件。 规范包括: ?自动重新传输以纠正有缺陷的数据； ?称为微包的小型数据传输单元的格式； ?包含网络应用程序路由信息的消息结构； ?端到端以及链接到链接的校验和； ?并行信号的定时要求； ?使用铜同轴电缆的并行接口； ?连接到单独的本地光接口； ?一种链路级协议，最大距离为1km。

This part of ISO/IEC 11518 specifies a physical-level, point-to-point, full-duplex, link interface for reliable, flow-controlled transmission of user data at 6 400 Mbit/s per direction, across distances of up to 1 km. A parallel copper cable interface for distances of up to 40 m is specified. Connections to a separate longer-distance optical interface are provided. Small fixed-size micropackets provide an efficient, low-latency structure for small transfers, and a component for large transfers. Specifications are included for: ?automatic retransmission to correct flawed data; ?the format of a small data transfer unit called a micropacket; ?a message structure that includes routing information for network applications; ?end-to-end, as well as link-to-link, checksums; ?the timing requirements of the parallel signals; ?a parallel interface using copper coaxial cable; ?connections to a separate local optical interface; ?a link-level protocol tuned for a maximum distance of 1 km.