Table of contents

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1.1 Purpose

1.2 Dependencies on Other Specifications

1.3 Documentation Conventions and Terminology

2 Conceptual Framework

2.1 Overview of XML Schema

2.2 XML Schema Abstract Data Model

2.2.1 Type Definition Components

2.2.2 Declaration Components

2.2.3 Model Group Components

2.2.4 Identity-constraint Definition Components

2.2.5 Group Definition Components

2.2.6 Annotation Components

2.3 Constraints and Validation Rules

2.4 Conformance

2.5 Names and Symbol Spaces

2.6 Schema-Related Markup in Documents Being Validated

2.6.1 xsi:type

2.6.2 xsi:nil

2.6.3 xsi:schemaLocation, xsi:noNamespaceSchemaLocation

2.7 Representation of Schemas on the World Wide Web

3 Schema Component Details

3.1 Introduction

3.1.1 Components and Properties

3.1.2 XML Representations of Components

3.1.3 The Mapping between XML Representations and Components

3.1.4 White Space Normalization during Validation

3.2 Attribute Declarations

3.2.1 The Attribute Declaration Schema Component

3.2.2 XML Representation of Attribute Declaration Schema Components

3.2.3 Constraints on XML Representations of Attribute Declarations

3.2.4 Attribute Declaration Validation Rules

3.2.5 Attribute Declaration Information Set Contributions

3.2.6 Constraints on Attribute Declaration Schema Components

3.2.7 Built-in Attribute Declarations

3.3 Element Declarations

3.3.1 The Element Declaration Schema Component

3.3.2 XML Representation of Element Declaration Schema Components

3.3.3 Constraints on XML Representations of Element Declarations

3.3.4 Element Declaration Validation Rules

3.3.5 Element Declaration Information Set Contributions

3.3.6 Constraints on Element Declaration Schema Components

3.4 Complex Type Definitions

3.4.1 The Complex Type Definition Schema Component

3.4.2 XML Representation of Complex Type Definitions

3.4.3 Constraints on XML Representations of Complex Type Definitions

3.4.4 Complex Type Definition Validation Rules

3.4.5 Complex Type Definition Information Set Contributions

3.4.6 Constraints on Complex Type Definition Schema Components

3.4.7 Built-in Complex Type Definition

3.5 AttributeUses

3.5.1 The Attribute Use Schema Component

3.5.2 XML Representation of Attribute Use Components

3.5.3 Constraints on XML Representations of Attribute Uses

3.5.4 Attribute Use Validation Rules

3.5.5 Attribute Use Information Set Contributions

3.5.6 Constraints on Attribute Use Schema Components

3.6 Attribute Group Definitions

3.6.1 The Attribute Group Definition Schema Component

3.6.2 XML Representation of Attribute Group Definition Schema Components

3.6.3 Constraints on XML Representations of Attribute Group Definitions

3.6.4 Attribute Group Definition Validation Rules

3.6.5 Attribute Group Definition Information Set Contributions

3.6.6 Constraints on Attribute Group Definition Schema Components

3.7 Model Group Definitions

3.7.1 The Model Group Definition Schema Component

3.7.2 XML Representation of Model Group Definition Schema Components

3.7.3 Constraints on XML Representations of Model Group Definitions

3.7.4 Model Group Definition Validation Rules

3.7.5 Model Group Definition Information Set Contributions

3.7.6 Constraints on Model Group Definition Schema Components

3.8 Model Groups

3.8.1 The Model Group Schema Component

3.8.2 XML Representation of Model Group Schema Components

3.8.3 Constraints on XML Representations of Model Groups

3.8.4 Model Group Validation Rules

3.8.5 Model Group Information Set Contributions

3.8.6 Constraints on Model Group Schema Components

3.9 Particles

3.9.1 The Particle Schema Component

3.9.2 XML Representation of Particle Components

3.9.3 Constraints on XML Representations of Particles

3.9.4 Particle Validation Rules

3.9.5 Particle Information Set Contributions

3.9.6 Constraints on Particle Schema Components

3.10 Wildcards

3.10.1 The Wildcard Schema Component

3.10.2 XML Representation of Wildcard Schema Components

3.10.3 Constraints on XML Representations of Wildcards

3.10.4 Wildcard Validation Rules

3.10.5 Wildcard Information Set Contributions

3.10.6 Constraints on Wildcard Schema Components

3.11 Identity-constraint Definitions

3.11.1 The Identity-constraint Definition Schema Component

3.11.2 XML Representation of Identity-constraint Definition Schema Components

3.11.3 Constraints on XML Representations of Identity-constraint Definitions

3.11.4 Identity-constraint Definition Validation Rules

3.11.5 Identity-constraint Definition Information Set Contributions

3.11.6 Constraints on Identity-constraint Definition Schema Components

3.12 Notation Declarations

3.12.1 The Notation Declaration Schema Component

3.12.2 XML Representation of Notation Declaration Schema Components

3.12.3 Constraints on XML Representations of Notation Declarations

3.12.4 Notation Declaration Validation Rules

3.12.5 Notation Declaration Information Set Contributions

3.12.6 Constraints on Notation Declaration Schema Components

3.13 Annotations

3.13.1 The Annotation Schema Component

3.13.2 XML Representation of Annotation Schema Components

3.13.3 Constraints on XML Representations of Annotations

3.13.4 Annotation Validation Rules

3.13.5 Annotation Information Set Contributions

3.13.6 Constraints on Annotation Schema Components

3.14 Simple Type Definitions

3.14.1 (non-normative) The Simple Type Definition Schema Component

3.14.2 (non-normative) XML Representation of Simple Type Definition Schema Components

3.14.3 (non-normative) Constraints on XML Representations of Simple Type Definitions

3.14.4 Simple Type Definition Validation Rules

3.14.5 Simple Type Definition Information Set Contributions

3.14.6 Constraints on Simple Type Definition Schema Components

3.14.7 Built-in Simple Type Definition

3.15 Schemas as a Whole

3.15.1 The Schema Itself

3.15.2 XML Representations of Schemas

3.15.3 Constraints on XML Representations of Schemas

3.15.4 Validation Rules for Schemas as a Whole

3.15.5 Schema Information Set Contributions

3.15.6 Constraints on Schemas as a Whole

4 Schemas and Namespaces: Access and Composition

4.1 Layer 1: Summary of the Schema-validity Assessment Core

4.2 Layer 2: Schema Documents, Namespaces and Composition

4.2.1 Assembling a schema for a single target namespace from multiple schema definition documents

4.2.2 Including modified component definitions

4.2.3 References to schema components across namespaces

4.3 Layer 3: Schema Document Access and Web-interoperability

4.3.1 Standards for representation of schemas and retrieval of schema documents on the Web

4.3.2 How schema definitions are located on the Web

5 Schemas and Schema-validity Assessment

5.1 Errors in Schema Construction and Structure

5.2 Assessing Schema-Validity

5.3 Missing Sub-components

5.4 Responsibilities of Schema-aware Processors

Appendices

A Schema for Schemas (normative)

B References (normative)

C Outcome Tabulations (normative)

C.1 Validation Rules

C.2 Contributions to the post-schema-validation infoset

C.3 Schema Representation Constraints

C.4 Schema Component Constraints

D Required Information Set Items and Properties (normative)

E Schema Components Diagram (non-normative)

F Glossary (non-normative)

G DTD for Schemas (non-normative)

H Analysis of the Unique Particle Attribution Constraint (non-normative)

I References (non-normative)

J Acknowledgements (non-normative)

2.4 Conformance

Conformance

This specification describes three levels of conformance for schema aware processors. The first is required of all processors. Support for the other two will depend on the application environments for which the processor is intended.

Minimally conforming processors must completely and correctly implement the Schema Component Constraint, Validation Rules, and Schema Information Set Contribution contained in this specification.

minimally conforming processors which accept schemas represented in the form of XML documents as described in [Layer 2: Schema Documents, Namespaces and Composition] are additionally said to provide conformance to the XML Representation of Schemas. Such processors must, when processing schema documents, completely and correctly implement all Schema Representation Constraint in this specification, and must adhere exactly to the specifications in [Schema Component Details] for mapping the contents of such documents to schema component for use in valid and assessment.

NOTE:
By separating the conformance requirements relating to the concrete syntax of XML schema documents, this specification admits processors which use schemas stored in optimized binary representations, dynamically created schemas represented as programming language data structures, or implementations in which particular schemas are compiled into executable code such as C or Java. Such processors can be said to be minimally conforming but not necessarily in conformance to the XML Representation of Schemas.

Fully conforming processors are network-enabled processors which are not only both minimally conforming and conformance to the XML Representation of Schemas, but which additionally must be capable of accessing schema documents from the World Wide Web according to [Representation of Schemas on the World Wide Web] and [How schema definitions are located on the Web]. .

NOTE:
Although this specification provides just these three standard levels of conformance, it is anticipated that other conventions can be established in the future. For example, the World Wide Web Consortium is considering conventions for packaging on the Web a variety of resources relating to individual documents and namespaces. Should such developments lead to new conventions for representing schemas, or for accessing them on the Web, new levels of conformance can be established and named at that time. There is no need to modify or republish this specification to define such additional levels of conformance.

See [Schemas and Namespaces: Access and Composition] for a more detailed explanation of the mechanisms supporting these levels of conformance.

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