Presently the discussion about the ISO Reference Model (RM, [1],[2]) is hardly un derstandable for insiders - there is no chance for outsiders to find out from the documents, what is going on. The two main reasons for this situation seem to be that we are concerned with an area in which the semantical notions (it is based on) are not yet really understood and which must span the huge distance between communica tions oriented towards telephone lines and communications oriented towards human beings. One way out of this unsatisfactory situation might be to try to immediately improve the notions and notations used in the RM in order to make it comprehensive, for in siders as well as for outsiders. We do not take this approach - simply because the chance of success of merely theoretical and/or conceptual efforts might be question able. Instead, one may try to contribute to improving the RM by elaborating on the structure proposed by the RM and designing/specifying/implementing systems neatly realizing it. For outsiders, systems of this kind would make it easier to get fami liar with the functional decomposition of the communications area, as recommended by the RM; for insiders they are necessary, as well, for improving our today's under standing of the peculiarities of the various parts of this area. Notions and nota tions then may be adjusted appropriately.

Inhalt
Der Datex-Dienst mit Paketvermittlung (DATEX-P).- The Addressing Requirements of a Transport-Service.- The OSA Project Design and Formal Specification of an X.25 Based Open Transport Layer and its Protocols.- Benutzerschnittstelle des PIX End-zu-End Protokolls.- UK Network Independent File Transfer Protocol.- Das Virtual device protocol (VDP).- JOB Transfer in Open Systems.- Rechnerverbund im Bildschirmtext.- Standardisierungsfragen und Realisierungserfahrungen bei Kommunikationsprotokollen in einem inhomogenen Rechnerverbundnetz.- Spezielle VT-Implementationsprobleme.- Architektur offener Kommunikationssysteme Stand der Normungsarbeit.- Systems Network Architecture in Relationship with the Open Systems Interconnection Reference Model.- Die Architektur des Siemens Datenfernverarbeitungssystems TRANSDATA im Vergleich zum ISO-Referenz-Modell.- Öffnung homogener geschlossener Herstellernetze im Sinne des ISO-Referenzmodells, am Beispiel von SNATCH, einem Funktionsverbund zwischen Siemens-TRANSDATA- und IBM-SNA-Rechnernetzen.- Vergleich der Struktur des CDAEG-Netzes mit dem ISO-Referenzmodell.- Process Communication Structures for Distributed Systems.- Zur Programmierung verteilter Systeme.