DIN EN 61158-4-3:2015-09

Nationales Vorwort
Nationaler Anhang NA (informative)
Foreword
INTRODUCTION
1 Scope
2 Normative references
3 Terms, definitions, symbols and abbreviations
4 Common DL-protocol elements
5 Overview of the DL-protocol
6 General structure and encoding of DLPDUs,
  and related elements of procedure
7 DLPDU-specific structure, encoding and elements
  of procedure
8 Other DLE elements of procedure
Annex A (normative) - DL-Protocol state machines
Annex B (informative) - Type 3 (synchronous): exemplary
        FCS implementations
Annex C (informative) - Type 3: Exemplary token procedure
        and message transfer periods.
Bibliography
Annex ZA (normative) - Normative references to
         international publications with their
         corresponding European publications

Gives communication opportunities to a pre-selected 'master' subset of data-link entities in a cyclic asynchronous manner, sequentially to each of those data-link entities.