ISO/IEC INTERNATIONAL STANDARD 11558 First edition 1992-09-01 Information technology --. Data compression for information interchange - Adaptive coding with embedded dictionary - DCLZ Algorithm Technologies de I'information - Compression de donnees pour I'éechange d'information - Codage adaptif avec un dictionnaire incorporé - Algorithme DCLZ Reference number ISO/IEC 11558:1992(E) Copyright International Organization for Standardization etworking permitted without license from IHS Not for Resale ISO/IEC 11558:1992 (E) Page Contents Scope 1 1 Conformance 1 2 1 3 Normative references Definitions 1 4 1 4.1 Code Value 1 4.2 Codeword 1 4.3 compression ratio 1 4.4 dictionary 1 4.5 empty state 1 4.6 frozen state 1 5 Conventions and notations 6 Algorithm identifier DCLZ compression algorithm 2 7 7.1 Overview 2 2 7.2 Principle of operation 7.2.1 Compilation of the dictionary 2 7.2.2 Frozen dictionary 2 3 7.2.3 Resetting the dictionary to the empty state 7.2.4 Boundaries 3 7.2.5 Re-creation of the dictionary 3 7.3 Code Values 3 3 7.3.1 Control Codes 7.3.2 Encoded Bytes 4 7.3.3 Dictionary Codes 4 4 7.4 Codewords Annexes 5 A - Example of a generic DCLZ algorithm 9 B - Example of Code Values output for a given input stream C - Bibliography 10 @ ISO/IEC 1992 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from the publisher. ISO/IEC Copyright Office · Case postale 56 · CH-1211 Geneve 20 · Switzerland Printed in Switzerland ii Copyright International Organization for Standardization without license from IHS Not for Resale ISO/IEC 11558:1992 (E) Foreword ISO (the International Organization for Standardization) and IEC (the Inter- national Electrotechnical Commission) form the specialized system for world- wide standardization. National bodies that are members of ISO or IEC partici- pate in the development of International Standards through technical committees established by the respective organization to deal with particular fields of mutual interest. Other international organizations, governmental and non- governmental, in liaison with ISO and IEC, also take part in the work. In the field of information technology, ISO and IEC have established a joint technical committee, ISO/IEC JTC 1. Draft International Standards adopted by the joint technical committee are circulated to national bodies for voting. Publi- cation as an International Standard requires approval by at least 75 % of the national bodies casting a vote. International Standard ISO/IEC 11558 was prepared by the European Computer Manufacturers Association (as Standard ECMA-151) and was adopted, under a special "fast-track procedure", by Joint Technical Committee ISO/IEC JTC 1, Information technology, in parallel with its approval by national bodies of ISO and IEC Annexes A to C of this International Standard are for information only Patents During the preparation of the ECMA standard, information was gathered on patents upon which application of the standard might depend. Relevant patents were identified as belonging to Hewlett Packard Limited. However, neither ECMA nor ISO/IEC can give authoritative or comprehensive information about evidence, validity or scope of patent and like rights. The patent holders have stated that licences will be granted under reasonable and non-discriminatory terms. Communications on this subject should be addressed to Hewlett Packard Limited Computer Peripherals Bristol Filton road Stoke Gifford Bristol BS12 6QZ United Kingdom iii Copyright International Organization for Standardization Not for Resale sefromIHS