本文献定义了对HDLC的扩充内容,使所有基于HDLC的通信规程,包括准备用于异步通信链路中全部过程的级别、成分和帧格式。本文并不是定义一个什么新的规程,只是替换HDLC最低层帧结构。文中并没提出对包括AFT(异步成帧技术)在内的其它标准进行特别修正,仅留作将来一旦AFT的原则和概念被接受之后,再做进一步研究。 This document defines an extension to HDLC that enables all HDLC-based communication protocols, including levels, components, and frame formats to be prepared for the full process in an asynchronous communication link. This article does not define a new procedure, but replaces the lowest-level HDLC frame structure. No specific amendments to other standards, including AFT (Asynchronous Framing Technology), have been proposed and should be made only for future studies once the principles and concepts of AFT have been accepted.