ISO INTERNATIONAL STANDARD 8601-2 First edition 2019-02 Date and time Representations for information interchange Part 2: Extensions Date et heure - Représentations pour I'échange d'information - Partie2:Extensions Reference number ISO 8601-2:2019(E) ISO @ IS0 2019 IS0 8601-2:2019(E) COPYRIGHTPROTECTEDDOCUMENT @ ISO 2019 All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either IsO at the address below or Iso's member body in the country of the requester. ISO copyright office CP 401 : Ch. de Blandonnet 8 CH-1214 Vernier, Geneva Phone: +4122 749 0111 Fax: +41 22 749 09 47 Email: [email protected] Website: www.iso.org Published in Switzerland ii @ IS0 2019 - All rights reserved IS0 8601-2:2019(E) Contents Page Foreword ..vii Introduction.. ..vili 1 Scope. 2 Normative references 3 Terms, definitions, symbols and abbreviated terms. 3.1 Terms and definitions .2 3.1.1 Basic concepts 3.1.2 Feature description. .2 3.1.3 Seasons 3.2 Symbols and abbreviated terms. 4 3.2.1 General ..4 3.2.2 Time scale component symbols. 4 3.2.3 Composite component symbols. .5 3.2.4 Symbols used to represent time scale component features ..6 3.2.5 Symbols used in date and time representations .6 3.2.6 Designator symbols used in date and time expressions. 3.2.7 Component symbols, representations and expressions. .7 4 Extensions to time scale components and units ..8 4.1 General 4.2 Order of time scale units. ..8 4.3 Additional explicit forms ..8 4.3.1 .8 General. 4.3.2 Value prefixing.. .8 4.3.3 Calendar day of week .8 4.3.4 Calendar day of year 9 4.3.5 Decade. 9 4.3.6 Century .9 4.4 Numerical extensions 4.4.1 Negative values. 9 4.4.2 Exponential values .12 4.4.3 Significant digits .13 4.5 Qualification of uncertainty and approximation ..13 4.6 Unspecified digits ..14 4.6.1 General .14 4.6.2 Unspecified time component value in explicit forms ..14 4.6.3 Unspecified time component digits in implicit forms .14 4.7 Expanded calendar year. .14 4.7.1 General. .14 4.7.2 Letter-prefixed calendar year .. 15 4.7.3 Exponential calendar year ..15 4.7.4 Significant digits ..15 4.8 Sub-year groupings. .15 4.8.1 Listing of seasons and common sub-year groupings ..15 4.8.2 Groupings represented as time scale components. ..16 4.8.3 Groupings represented as months ..16 5 Grouped time scale units ..17 5.1 General ..17 5.2 Unit definition. .17 5.3 Unit value... ..18 5.4 Application within representations ..18 5.4.1 General. ..18 5.4.2 Use of grouped units. ..18 @ IS0 2019 - All rights reserved iii