ISO INTERNATIONAL STANDARD 8807 First edition 1989-02-15 Information processing systems -- Open Systems Interconnection -- LOTOS A formal description technique based on the temporal ordering of observational behaviour Systemes de traitement de I'information - Interconnexion de systemes ouverts LOTOS - Technique de description formelle basee sur I'organisation temporelle de comportementobservationnel Reference number ISO8807:1989 (E) Copyright Intermational Organization for Standardization cense with IS rmitted without license from IHS Not for Resale ISO 8807 : 1988 (E) Foreword Iso (the International Organization for Standardization) is a worldwide federation of national standards bodies (IsO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, govern- mental and non-governmental, in liaison with Iso, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all mattersofelectrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for approval before their acceptance as International Standards by the ISO Council. They are approved in accordance with ISO procedures requiring at least 75 % approval by the member bodies voting. International Standard ISO 8807 was prepared by Technical Committee ISO/TC 97, Informationprocessing systems. Users should note that all International Standards undergo revision from time to time and that any reference made herein to any other International Standard implies its latest edition,unless otherwise stated Annex A forms an integral part of this International Standard. Annexes B, C, D and E are for information only. International Organization for Standardization, 1989 Printed in Switzerland ii Copyright International Organization for Standardization bermitted without license from IHS Not for Resale ISO 8807 : 1989 (E) CONTENTS Page 0 Introduction 0.1 General 0.2 FDTs 0.3 The requirement for standard FDTs 0.4 The objectives to be satisfied by an FDT 0.5 The origin of LOTOS 2 0.6 The structure of this International Standard 2 Scope and field of application .3 2 References .3 3 Conformance .3 Basic mathematical concepts and notation .5 4 4.1 General 5 4.2 Sets 5 4.3 Lists 6 4.4 Strings 9 4.5 Relationsandfunctions 6 4.6 Backus-Naur Form 7 4.7 Syntax-directed definitions 8 4.8 Derivation systems .10 Model 13 5.1 Introduction 13 5.2 Many-sorted algebras .13 5.3 Labelled transition systems .13 5.4 Structured labelled transition systems .14 Formal Syntax .15 6.1 Lexicaltokens 15 6.1.1 General .15 6.1.2 Basic characters 15 6.1.3 Reserved symbols 15 6.1.3.1 Word symbols 15 6.1.3.2 Special symbols .17 6.1.4 Identifiers 17 6.1.5 Requirement 18 6.1.6 Comments 18 6.1.7 Token separators .18 6.1.8 Requirement 18 6.2 Specification text 18 6.2.1 specification .18 6.2.2 definition-block 18 6.2.3 data-type-definitions 19 6.2.4 p-expressions .19 6.2.5 sorts, operations and equations 19 6.2.6 process-definitions 20 6.2.7 behaviour-expressions .20 6.2.7.1 general structure 21 6.2.7.2 local-definition-expressions .21 6.2.7.3 sum-expressions 21 ili Not for Resale ISO 8807 : 1989 (E) 6.2.7.4 par-expressions .21 6.2.7.5 hiding-expressions 21 6.2.7.6 enable-expressions. 21 6.2.7.7 disable-expressions 22 6.2.7.8 parallel-expressions 22 6.2.7.9 choice-expressions 22 6.2.7.10 guarded-expressions .22 6.2.7.11 action-prefix-expressions 22 6.2.7.12 atomic-expressions 22 6.2.8 value-expressions 23 6.2.9 declarations .23 6.2.10 special-identifiers . 23 7 Semantics .25 7.1 Introduction .25 7.1.1 Structure of the static semantics definition .25 7.1.2 Structure of the dynamic semantics definition .25 7.1.3 Structure of clause 7 .26 7.2 Generat structures and definitio