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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.
Technical content elements
Elements in the technical content section include the original Concept, Task, and Reference specializations, as well as specializations added in later releases. It also includes domains designed primarily for technical content.
Technical-content domains elements
Domains in this section include those generally associated with technical content, such as the programming and software domains.
Equation domain elements
The elements in the equation domain enable authors to clearly distinguish equations from other type of content. These markup distinctions can enable formatting distinctions, numbering of equations, and more. This domain can be used independently of the MathML domain.
equation-number
Use the <equation-number> element to indicate that a block equation is numbered and, optionally, to specify the number to use for the block equation.

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.
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.
- Element quick reference
  This section contains a listing of DITA elements.
- Topic elements
  The base topic elements include elements that make up the core building blocks of the DITA topic, such as topic, body, and related-links, as well as elements like <p> and <ph> that are used in many topic specializations. Some of these elements are also available inside the <topicmeta> map element.
- Map elements
  Map elements include the core components of DITA maps, such as <topicref> and <reltable>, as well as general purpose map specializations in the map group domain.
- Metadata elements
  Metadata elements include information that is located within the <topicmeta> element (in maps) or <prolog> element (in topics), as well as indexing elements that can be placed in additional locations within topic content.
- Domain elements
  General purpose domains are not specific to any type of information, such as the hazard statement domain that provides elements for describing hazardous situations.
- Classification elements
  Classification elements support managing metadata. Those in the subject scheme map are used to define controlled values and to bind the controlled values to DITA attributes as enumerations. Those declared in the classification domain are used in other maps to classify content according to the scheme.
- Specialization elements
  Several DITA elements exist either for architectural reasons or for support of specialized markup yet to be designed. Although there is little need to use these elements unless you are directed to, some of them, such as <state>, can be used if your content makes use of these semantic distinctions. For example, a discussion of signals on a gate of an integrated logic circuit might use the <state> element to represent either on or off conditions of that gate.
- Legacy conversion elements
  Conversion elements exist primarily to aid in the conversion of content to DITA.
- DITAVAL elements
  A conditional processing profile (DITAVAL file) is used to identify which values are to be used for conditional processing during a particular output, build, or some other purpose. The profile should have an extension of .ditaval.
- Technical content elements
  Elements in the technical content section include the original Concept, Task, and Reference specializations, as well as specializations added in later releases. It also includes domains designed primarily for technical content.
  - Concept elements
    DITA concept topics answer "What is..." questions. Use the concept topic to introduce the background or overview information for tasks or reference topics. The concept topic restricts content following a section or example to other sections or examples. For more details on when to use concept and other information types, please refer to the DITA architectural specification.
  - Task elements
    Task topics answer "How do I?" questions, and have a well-defined structure that describes how to complete a procedure to accomplish a specific goal. Use the task topic to describe the steps of a particular task, or to provide an overview of a higher-level task. The task topic includes sections for describing the context, prerequisites, actual steps, expected results, example, and expected next steps for a task. For more details on when to use task and other information types, please refer to the DITA architectural specification.
  - Reference elements
    Reference topics describe factual material about a subject, such as the commands in a programming language. This format is also suitable for bibliographies, catalogues, the list of ingredients for recipes, and similar collections of structured descriptive prose. For more details on when to use reference and other information types, please refer to the DITA architectural specification.
  - Troubleshooting elements
    Troubleshooting topics document corrective action such as troubleshooting or alarm clearing.
  - Glossary elements
    Glossary elements include those elements designed to specify terms and their definitions, as well as elements that are designed to group, reference, or otherwise make use of information in the glossentry topic.
  - Bookmap elements
    Elements in the bookmap section are used to organize DITA content into book form. They include elements for dividing up content, such as chapter and appendix, as well as metadata specific to publishing.
  - Technical-content domains elements
    Domains in this section include those generally associated with technical content, such as the programming and software domains.
    - Equation domain elements
      The elements in the equation domain enable authors to clearly distinguish equations from other type of content. These markup distinctions can enable formatting distinctions, numbering of equations, and more. This domain can be used independently of the MathML domain.
      - equation-block
        Use the <equation-block> element to represent an equation that is presented as a separate block within a text flow. Block equations can be numbered.
      - equation-figure
        Use the <equation-figure> element to represent an equation that functions as form of figure or display. Display equations are intended to be numbered when numbering is desired.
      - equation-inline
        Use the <equation-inline> element to represent an equation that is presented inline within a paragraph or similar context. Inline equations are not intended to be numbered.
      - equation-number
        Use the <equation-number> element to indicate that a block equation is numbered and, optionally, to specify the number to use for the block equation.
    - Markup domain
      The markup domain elements are used for the mention of named constructs in markup languages, such as XML.
    - MathML domain elements
      The MathML domain elements enable direct use of MathML markup within DITA documents, as well as use-by-reference of MathML markup that is stored separate, non-DITA documents. MathML is a W3C standard.
    - Programming elements
      The programming domain elements are used to define the syntax for programming languages. They also can be used to provide examples.
    - Release-management domain elements
      The release-management domain elements contain human-authored information about the changes that have been made to a DITA topic or map. A processor can retrieve this information and use it to assemble documents or topics that contain release note information.
    - Software elements
      The software domain elements are used to describe the operation of a software program.
    - SVG elements
      The SVG domain elements enable direct use of SVG markup within DITA documents, as well as use-by-reference of SVG markup that is stored in separate non-DITA documents. SVG is a W3C standard.
    - Task requirements domain
      The task requirements domain contains elements for use in describing tasks that involve machines or other pieces of hardware.
    - User interface elements
      The user interface domain elements are used to describe the user interface of a software program.
    - XML mention domain
      Use the XML-mention domain elements for mentions of named XML constructs, including elements, attributes, entities, processing instructions, and document-type declaration components. These elements enable specific typographic effects for different construct types, precise search and retrieval of specific constructs, and automatic indexing of different constructs. This domain is intended to support the description and documentation of XML document types and XML applications.
    - xNAL domain elements
      The xNAL domain elements represent a subset of the Extensible Name and Address Standard. It is used to encode information about the author or authors of DITA information. The domain can be included in any DITA document type shell that requires additional metadata for names and addresses, although the implementations provided by OASIS only include it in the bookmap document type.
- Learning and training elements
  Elements in the learning and training section include specialized topics, maps, content, and metadata elements specially designed to support instructional content.
- Attributes
  This section collects commonly used attributes, with common definitions. If an element uses a different definition, or narrows the scope of, an otherwise common attribute, it will be called out in the topic that defines the element.
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.

`<equation-number>`

Use the <equation-number> element to indicate that a block equation is numbered and, optionally, to specify the number to use for the block equation.

When the <equation-number> element has empty or whitespace-only content, the equation number SHOULD be generated. When the <equation-number> element has non-whitespace-only content the content SHOULD be used as the equation number. For explicit numbers the content of the element SHOULD be the number value without any surrounding punctuation, for example, "3.2a" rather than "(3.2a)". Processors SHOULD add punctuation or decoration to the number as appropriate.

In normal usage a block equation will have at most one number. However, <equation-number> can occur multiple times within <equation-block>, for example, to allow numbers with different (and exclusive) conditional properties.

The details of equation numbering and number presentation are processor-specific. However, common practice is to present the equation number to the right of the equation, centered vertically within the vertical extent of the block equation.

Content models

See appendix for information about this element in OASIS document type shells.

Inheritance

+ topic/ph equation-d/equation-number

Example

An equation with a generated number:

<p>A block equation using an image:</p>
<equation-block id="eq-001">
  <equation-number/>
  <image keyref="equation-image-01">
    <alt>a squared plus b squared.</alt>
  </image>
</equation-block>

An equation with an explicit number:

<p>A block equation using an image:</p>
<equation-block id="eq-3.2a">
  <equation-number>3.2a</equation-number>
  <image keyref="equation-image-01">
    <alt>a squared plus b squared.</alt>
  </image>
</equation-block>

Attributes

The following attributes are available on this element: Universal attribute group and outputclass.