WIXLIB

DefinitiveXMLSchemaSecond Edition

The Charles F. GoldfarbDefinitive XML SeriesPriscilla WalmsleyDefinitive XML Schema Second EditionCharles F. Goldfarb and Paul PrescodCharles F. Goldfarb’s XML Handbook Fifth EditionRick JelliffeThe XML and SGML Cookbook:Recipes for Structured InformationCharles F. Goldfarb, Steve Pepper,and Chet EnsignSGML Buyer’s Guide: Choosing the RightXML and SGML Products and ServicesG. Ken HolmanDefinitive XSL-FODefinitive XSLT and XPathBob DuCharmeXML: The Annotated SpecificationSGML CDTruly DonovanIndustrial-Strength SGML:An Introduction to Enterprise PublishingLars Marius GarsholDefinitive XML Application DevelopmentJP Morgenthal with Bill la ForgeEnterprise Application Integration withXML and JavaMichael Leventhal, David Lewis, andMatthew FuchsDesigning XML Internet ApplicationsAdam Hocek and David CuddihyDefinitive VoiceXMLDmitry KirsanovXSLT 2.0 Web DevelopmentYuri Rubinsky and Murray MaloneySGML on the Web:Small Steps Beyond HTMLDavid MegginsonStructuring XML DocumentsSean McGrathXML Processing with PythonXML by Example:Building E-commerce ApplicationsParseMe.1st:SGML for Software DevelopersChet Ensign GML: The Billion Dollar SecretRon Turner, Tim Douglass, andAudrey TurnerReadMe.1st:SGML for Writers and EditorsCharles F. Goldfarb andPriscilla WalmsleyXML in Office 2003:Information Sharing with Desktop XMLMichael FloydBuilding Web Sites with XMLFredrick Thomas MartinTOP SECRET Intranet:How U.S. Intelligence Built Intelink—TheWorld’s Largest, Most Secure NetworkJ. Craig CleavelandProgram Generators with XML and JavaAbout the Series AuthorCharles F. Goldfarb is the father of XML technology. He invented SGML, the StandardGeneralized Markup Language on which both XML and HTML are based. You can findhim on the Web at: www.xmlbooks.com.About the Series LogoThe rebus is an ancient literary tradition, dating from 16th century Picardy, and is especiallyappropriate to a series involving fine distinctions between markup and text, metadata anddata. The logo is a rebus incorporating the series name within a stylized XML commentdeclaration.

DefinitiveXMLSchemaSecond EditionPriscilla WalmsleyUpper Saddle River, NJ Boston Indianapolis San FranciscoNew York Toronto Montreal London Munich Paris MadridCape Town Sydney Tokyo Singapore Mexico City

Many of the designations used by manufacturers and sellers to distinguish their products areclaimed as trademarks. Where those designations appear in this book, and the publisher wasaware of a trademark claim, the designations have been printed with initial capital letters orin all capitals.The author and publisher have taken care in the preparation of this book, but make noexpressed or implied warranty of any kind and assume no responsibility for errors or omissions.No liability is assumed for incidental or consequential damages in connection with or arisingout of the use of the information or programs contained herein.Titles in this series are produced using XML, SGML, and/or XSL. XSL-FO documents arerendered into PDF by the XEP Rendering Engine from RenderX: www.renderx.com.The publisher offers excellent discounts on this book when ordered in quantity for bulkpurchases or special sales, which may include electronic versions and/or custom covers andcontent particular to your business, training goals, marketing focus, and branding interests.For more information, please contact:U.S. Corporate and Government Sales(800) 382–3419corpsales@pearsontechgroup.comFor sales outside the United States, please contact:International Salesinternational@pearsoned.comVisit us on the Web: informit.com/phLibrary of Congress Cataloging-in-Publication Data is on fileCopyright 2013 Pearson Education, Inc.All rights reserved. Printed in the United States of America. This publication is protected bycopyright, and permission must be obtained from the publisher prior to any prohibitedreproduction, storage in a retrieval system, or transmission in any form or by any means,electronic, mechanical, photocopying, recording, or likewise. To obtain permission to usematerial from this work, please submit a written request to Pearson Education, Inc.,Permissions Department, One Lake Street, Upper Saddle River, New Jersey 07458, or youmay fax your request to (201) 236–3290.ISBN-13: 978-0-132-88672-7ISBN-10: 0-132-88672-3Text printed in the United States on recycled paper at Edwards Brothers Malloy in AnnArbor, MI.First printing: September 2012Editor-in-Chief: Mark L. TaubManaging Editor: Kristy HartBook Packager: Alina KirsanovaCover Designer: Alan Clements

To Doug, my SH

This page intentionally left blank

OverviewChapter 1Schemas: An introductionChapter 2A quick tour of XML Schema16Chapter 3Namespaces34Chapter 4Schema composition56Chapter 5Instances and schemas78Chapter 6Element declarations88Chapter 7Attribute declarations112Chapter 8Simple types128Chapter 9Regular expressions1582Chapter 10Union and list types180Chapter 11Built-in simple types200Chapter 12Complex types256Chapter 13Deriving complex types300Chapter 14Assertions350Chapter 15Named groups384Chapter 16Substitution groups406Chapter 17Identity constraints422vii

viiiOverviewRedefining and overriding schemacomponents446Chapter 19Topics for DTD users472Chapter 20XML information modeling500Chapter 21Schema design and documentation538Chapter 22Extensibility and reuse594Chapter 23Versioning616Chapter 18Appendix AXSD keywords648Appendix BBuilt-in simple types690

ContentsForewordAcknowledgmentsHow to use this bookChapter 1 Schemas: An introductionWhat is a schema?1.1The purpose of schemas1.2xxxixxxiiixxxv2351.2.1Data validation51.2.2A contract with trading partners51.2.3System documentation61.2.4Providing information to processors61.2.5Augmentation of data61.2.6Application information61.3Schema design71.3.1Accuracy and precision71.3.2Clarity81.3.3Broad applicability8ix

xContents1.4Schema languages91.4.1Document Type Definition (DTD)1.4.2Schema requirements expand101.4.3W3C XML Schema111.4.4Other schema languages121.4.4.11.4.4.2RELAX NGSchematronA quick tour of XML SchemaAn example schemaThe components of XML SchemaChapter 22.12.2912131617182.2.1Declarations vs. definitions182.2.2Global vs. local components192.3Elements and attributes20The tag/type distinction202.3.12.4Types212.4.1Simple vs. complex types212.4.2Named vs. anonymous types222.4.3The type definition hierarchy222.5Simple types232.5.1Built-in simple types232.5.2Restricting simple types242.5.3List and union types24Complex types252.6.1Content types252.6.2Content models262.6.3Deriving complex types272.62.7Namespaces and XML Schema28

Contents2.82.92.102.11Schema compositionInstances and schemasAnnotationsAdvanced features293031322.11.1Named groups322.11.2Identity constraints322.11.3Substitution groups322.11.4Redefinition and overriding332.11.5Assertions33NamespacesNamespaces in XMLChapter 33.134353.1.1Namespace names363.1.2Namespace declarations and prefixes373.1.3Default namespace declarations393.1.4Name terminology403.1.5Scope of namespace declarations413.1.6Overriding namespace declarations423.1.7Undeclaring namespaces433.1.8Attributes and namespaces443.1.9A summary example463.23.3The relationship between namespaces andschemasUsing namespaces in schemas48483.3.1Target namespaces483.3.2The XML Schema Namespace503.3.3The XML Schema Instance Namespace513.3.4The Version Control Namespace51xi

xiiContents3.3.5Namespace declarations in schema documentsMap a prefix to the XML Schema NamespaceMap a prefix to the target namespaceMap prefixes to all namespaces525354Schema compositionModularizing schema documentsDefining schema documentsCombining multiple schema documents563.3.5.13.3.5.23.3.5.3Chapter 44.14.24.34.3.1include4.3.1.1 The syntax of includes4.3.1.2 Chameleon includes575861626365import4.3.2.1 The syntax of imports4.3.2.2 Multiple levels of imports4.3.2.3 Multiple imports of the same namespace66Schema assembly considerations754.3.24.4526770724.4.1Uniqueness of qualified names754.4.2Missing components764.4.3Schema document defaults77Instances and schemasUsing the instance attributesSchema processingChapter 55.15.27879815.2.1Validation815.2.2Augmenting the instance825.3Relating instances to schemas5.3.15.3.1.15.3.1.25.4Using hints in the instanceThe xsi:schemaLocation attributeThe xsi:noNamespaceSchemaLocation attributeThe root element8384848687

ContentsElement declarationsGlobal and local element declarationsChapter 66.188896.1.1Global element declarations896.1.2Local element declarations936.1.3Design hint: Should I use global or local elementdeclarations?956.26.3Declaring the types of elementsQualified vs. unqualified forms96986.3.1Qualified local names986.3.2Unqualified local names986.3.3Using elementFormDefault996.3.4Using form1006.3.5Default namespaces and unqualified names1016.4Default and fixed values1016.4.1Default values1026.4.2Fixed values1036.5Nils and nillability1056.5.1Using xsi:nil in an instance1086.5.2Making elements nillable109Attribute declarationsAttributes vs. elementsGlobal and local attribute declarationsChapter 77.17.21121131157.2.1Global attribute declarations1157.2.2Local attribute declarations1177.2.3Design hint: Should I use global or local attributedeclarations?1197.3Declaring the types of attributes120xiii

xivContents7.47.5Qualified vs. unqualified formsDefault and fixed values1221237.5.1Default values1247.5.2Fixed values1257.6Inherited attributesSimple typesSimple type varietiesChapter 88.18.1.18.2Design hint: How much should I break down my datavalues?Simple type definitions1261281291301318.2.1Named simple types1318.2.2Anonymous simple types1328.2.3Design hint: Should I use named or anonymous types?1338.3Simple type restrictions1358.3.1Defining a restriction1368.3.2Overview of the facets1378.3.3Inheriting and restricting facets1398.3.4Fixed facets1408.3.4.18.4Design hint: When should I fix a facet?Facets1411428.4.1Bounds facets1428.4.2Length facets1438.4.2.18.4.2.2Design hint: What if I want to allow empty values?Design hint: What if I want to restrict the length of an integer?1431448.4.3totalDigits and 88.4.6Assertion150

Contents8.4.7Explicit Time Zone1508.4.8Whitespace151Preventing simple type derivationImplementation-defined types and facets8.58.61521548.6.1Implementation-defined types1548.6.2Implementation-defined facets155Regular expressionsThe structure of a regular expressionAtomsChapter 99.19.21581591619.2.1Normal characters1629.2.2The wildcard escape character1649.2.3Character class escapes164Single-character escapesMulticharacter escapesCategory escapesBlock racter class 59.2.4.69.2.59.39.4Listing individual charactersSpecifying a rangeCombining individual characters and rangesNegating a character class expressionSubtracting from a character class expressionEscaping rules for character class expressionsParenthesized regular expressionsQuantifiersBranchesUnion and list typesVarieties and derivation typesUnion typesChapter v

xviContents10.2.1Defining union types18310.2.2Restricting union types18510.2.3Unions of unions18610.2.4Specifying the member type in the instance18710.3List types18810.3.1Defining list types18810.3.2Design hint: When should I use lists?18910.3.3Restricting list types19010.3.3.110.3.3.210.3.3.3Length facetsEnumeration facetPattern facet19219219410.3.4Lists and strings19510.3.5Lists of unions19610.3.6Lists of lists19610.3.7Restricting the item type198Built-in simple typesThe XML Schema type systemChapter 1111.120020111.1.1The type hierarchy20211.1.2Value spaces and lexical spaces20411.1.3Facets and built-in types20411.2String-based types11.2.1 string, normalizedString,11.2.1.1205and tokenDesign hint: Should I use string, normalizedString,or token?20520711.2.2 Name20811.2.3 NCName21011.2.4 language21111.3Numeric types213