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Architectural specification: All-inclusive edition
The architectural specification portion of the DITA specification outlines the framework of DITA. It contains an overview of DITA markup; addressing; processing; configuration, specialization, generalization, and constraints; as well as information about coding DITA grammar files.
DITA addressing
DITA provides two addressing mechanisms. DITA addresses either are direct URI-based addresses, or they are indirect key-based addresses. Within DITA documents, individual elements are addressed by unique identifiers specified on the @id attribute. DITA defines two fragment-identifier syntaxes; one is the full fragment-identifier syntax, and the other is an abbreviated fragment-identifier syntax that can be used when addressing non-topic elements from within the same topic.
Indirect key-based addressing
DITA keys provide an alternative to direct addressing. The key reference mechanism provides a layer of indirection so that resources (for example, URIs, metadata, or variable text strings) can be defined at the DITA map level instead of locally in each topic.
Using keys for addressing
For topic references, image references, and other link relationships, resources can be indirectly addressed by using the @keyref attribute. For content reference relationships, resources can be indirectly addressed by using the @conkeyref attribute.

Specification URIs
Notices
Introduction to DITA 1.3
The Darwin Information Typing Architecture (DITA) specification defines a set of document types for authoring and organizing topic-oriented information, as well as a set of mechanisms for combining, extending, and constraining document types.
Architectural specification: All-inclusive edition
The architectural specification portion of the DITA specification outlines the framework of DITA. It contains an overview of DITA markup; addressing; processing; configuration, specialization, generalization, and constraints; as well as information about coding DITA grammar files.
- Introduction to DITA
  The Darwin Information Typing Architecture (DITA) is an XML-based architecture for authoring, producing, and delivering topic-oriented, information-typed content that can be reused and single-sourced in a variety of ways. While DITA historically has been driven by the requirements of large-scale technical documentation authoring, management, and delivery, it is a standard that is applicable to any kind of publication or information that might be presented to readers, including interactive training and educational materials, standards, reports, business documents, trade books, travel and nature guides, and more.
- DITA markup
  Topics and maps are the basic building blocks of the Darwin Information Typing Architecture (DITA). Metadata attributes and values can be added to DITA topics and maps, as well as to elements within topics, to allow for conditional publishing and content reuse.
- DITA addressing
  DITA provides two addressing mechanisms. DITA addresses either are direct URI-based addresses, or they are indirect key-based addresses. Within DITA documents, individual elements are addressed by unique identifiers specified on the @id attribute. DITA defines two fragment-identifier syntaxes; one is the full fragment-identifier syntax, and the other is an abbreviated fragment-identifier syntax that can be used when addressing non-topic elements from within the same topic.
  - ID attribute
    The @id attribute assigns an identifier to DITA elements so that the elements can be referenced.
  - DITA linking
    DITA supports many different linking elements, but they all use the same set of attributes to describe relationships between content.
  - URI-based (direct) addressing
    Content reference and link relationships can be established from DITA elements by using URI references. DITA uses URI references in @href, @conref, and other attributes for all direct addressing of resources.
  - Indirect key-based addressing
    DITA keys provide an alternative to direct addressing. The key reference mechanism provides a layer of indirection so that resources (for example, URIs, metadata, or variable text strings) can be defined at the DITA map level instead of locally in each topic.
    - Core concepts for working with keys
      The concepts described below are critical for a full understanding of keys and key processing.
    - Key scopes
      Key scopes enable map authors to specify different sets of key definitions for different map branches.
    - Using keys for addressing
      For topic references, image references, and other link relationships, resources can be indirectly addressed by using the @keyref attribute. For content reference relationships, resources can be indirectly addressed by using the @conkeyref attribute.
    - Addressing keys across scopes
      When referencing key definitions that are defined in a different key scope, key names might need to be qualified with key scope names.
    - Cross-deliverable addressing and linking
      A map can use scoped keys to reference keys that are defined in a different root map. This cross-deliverable addressing can support the production of deliverables that contain working links to other deliverables.
    - Processing key references
      Key references can resolve as links, as text, or as both. Within a map, they also can be used to create or supplement information on a topic reference. This topic covers information that is common to all key processing, regardless of how the key is used.
    - Processing key references for navigation links and images
      Keys can be used to create or redirect links and cross references. Keys also can be used to address resources such as images or videos. This topic explains how to evaluate key references on links and cross references to determine a link target.
    - Processing key references on <topicref> elements
      While <topicref> elements are used to define keys, they also can reference keys that are defined elsewhere. This topic explains how to evaluate key references on <topicref> elements and its specializations.
    - Processing key references to generate text or link text
      Key references can be used to pull text from the key definition. This topic explains how to generate text from a key definition, regardless of whether the key reference also results in a link.
    - Examples of keys
      This section of the specification contains examples and scenarios. They illustrate a wide variety of ways that keys can be used.
- DITA processing
  DITA processing is affected by a number of factors, including attributes that indicate the set of vocabulary and constraint modules on which a DITA document depends; navigation; linking; content reuse (using direct or indirect addressing); conditional processing; branch filtering; chunking; and more. In addition, translation of DITA content is expedited through the use of the @dir, @translate, and @xml:lang attributes, and the <index-sort-as> element.
- Configuration, specialization, generalization, and constraints
  The extension facilities of DITA allow existing vocabulary and constraint modules to be combined to create specific DITA document types. Vocabulary modules also can be specialized to meet requirements that are not satisfied by existing markup.
- Coding practices for DITA grammar files
  This section collects all of the rules for creating modular DTD, RELAX NG, or XML Schema grammar files to represent DITA document types, specializations, and constraints.
- Technical content specializations
  This section contains information about the technical content specializations. It includes a summary of the document types and domains, as well as information about how the technical content specializations support authoring troubleshooting information.
- Learning and training specializations
  The section contains information about the learning and training specializations: Challenges faced by developers of instructional content; use cases; objectives of the specializations; information about the reusable learning-objects approach to learning and training content; summary of the topic types and domains; and more.
Language reference: All-inclusive edition
The language reference portion of the DITA specification contains a topic for each DITA element. The topic defines the element, its inheritance hierarchy, and provides examples of usage. This portion of the DITA specification also includes information about DITA attributes.
Conformance
Conformance to the DITA specification allows documents and document types that are used with different processors or different versions of a processor to produce the same or similar results with little or no reimplementation or modification.
Acknowledgments
(Non-normative) Many members of the OASIS DITA Technical Committee participated in the creation of this specification and are gratefully acknowledged.
Non-normative information
This section contains non-normative information, including topics about new features in DITA 1.3 and migrating from DITA 1.2 to DITA 1.3.
Content models for learning and training package
For each element in the learning and training package, this section presents the content model and a list of parent elements that can contain that element.

Using keys for addressing

For topic references, image references, and other link relationships, resources can be indirectly addressed by using the @keyref attribute. For content reference relationships, resources can be indirectly addressed by using the @conkeyref attribute.

Syntax

For references to topics, maps, and non-DITA resources, the value of the @keyref attribute is simply a key name (for example, keyref="topic-key").

For references to non-topic elements within topics, the value of the @keyref attribute is a key name, a slash ("/"), and the ID of the target element (for example, keyref="topic-key/some-element-id".)

Example

For example, consider this topic in the document file.dita:

<topic id="topicid">
 <title>Example referenced topic</title>
 <body>
  <section id="section-01">Some content.</section>
 </body>
</topic>

and this key definition:

<map>
  <topicref keys="myexample"
    href="file.dita"
  />
</map>

A cross reference of the form keyref="myexample/section-01" resolves to the <section> element in the topic. The key reference is equivalent to the URI reference xref="file.dita#topicid/section-01".