This document is a revision to STD35@ RFC1006 written by Marshall T. Rose and Dwight E. Cass. Since the release of RFC1006 in May 1987@ much experience has been gained in using ISO transport services on top of TCP. This document refines the protocol and will eventually supersede RFC1006. This document describes the mechanism to allow ISO Transport Services to run over TCP over IPv4 or IPv6. It also defines a number of new features@ which are not provided in RFC1006. The goal of this version is to minimise the number of changes to RFC1006 and ISO 8073 transport protocol definitions@ while maximising performance@ extending its applicability and protecting the installed base of RFC1006 users.