This amendment is one of a set of amendments to the OS1 upper-layers standards produced to facilitate the interconnection of information processing systems in an open environment where efficiency of communications is paramount. Such efficiencies include: a) reduction in the overhead needed to encode control information for use in bandwidth-limited environments (such as radio links) or processing-limited systems (such as switching systems); b) reduction in the delay to set up the association between the communicating applications so that data transfer can begin expeditiously; c) reduction in the support of unneeded functionality in certain environments where the communications requirements of the applications are limited.