指定由ITU-T Rec.X.233 ISO/IEC 8473-1定义的协议所承担的底层服务由提供CCITT Rec.X.212 ISO/IEC 8886定义的OSI数据链路服务的子网通过ISO/IEC 8648中描述的子网相关汇聚功能（SNDCF）的操作来提供的方式。还根据相关要求和相关指南提供了本协议的PICS形式表。

Specifies the way in which the underlying service assumed by the protocol defined by ITU-T Rec. X.233 ISO/IEC 8473-1 is provided by a subnetwork that provides the OSI Data Link service defined by CCITT Rec. X.212 ISO/IEC 8886, through the operation of a Subnetwork Dependent Convergence Function (SNDCF) as described in ISO/IEC 8648. Also provides the PICS proforma for this protocol, in compliance with the relevant requirements and in accordance with the relevant guidance.