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Cross-referencing
Cross-references are a means of binding individual topics into a coherent and navigable document.
Cross-referencing topics and external resources
Cross-references are commonly made to other DITA topics in a collection, and to information resources outside the collection. These external targets can be any type of electronic resource that can be addressed through a URI, including e-mail addresses, documents on a network file server, and Web content.
Format of href attribute in cross-references
The href attribute requires the address of the referenced resource to be in the standard URI format.

Introduction
Information types and topics
Topics are the building blocks of modular documents, and organising topics by semantic information types is one of the architectural features of DITA.
DITA map files
Syntax and mark-up
Language and punctuation
Graphics and figures
Cross-referencing
Cross-references are a means of binding individual topics into a coherent and navigable document.
- Types of cross-references
  A cross-reference is used in DITA to link or associate one piece of content with another. The cross-reference (xref) element is the primary mechanism for cross-referencing, but other elements also have cross-referencing functions.
- The xref element
  The cross-reference element is used for linking or otherwise cross-referencing text within a topic to other topics, elements within a topic, or resources external to the DITA collection.
- Avoiding in-text cross-references to topics
  Cross-references to other topics should be stored in the relationship table of the ditamap, external to the topic, and not in-line within the text of the topic.
- Cross-referencing topics and external resources
  Cross-references are commonly made to other DITA topics in a collection, and to information resources outside the collection. These external targets can be any type of electronic resource that can be addressed through a URI, including e-mail addresses, documents on a network file server, and Web content.
  - Format of href attribute in cross-references
    The href attribute requires the address of the referenced resource to be in the standard URI format.
  - Links to non-DITA resources
    Cross-references can be used to link from within DITA topics to non-DITA resources, such as Web URLs, e-mail addresses, and documents stored on file servers. The scope and format attributes of the cross-reference are used to define the nature of the linked resource, and indirectly the way the link will behave.
  - Linking in a new window
    The scope attribute of the cross-reference (xref) is used to nominate whether the target topic, file or other resource is external to the DITA source topics. Some publishing tools (such as the DITA Open Toolkit) will generate cross-references with an external scope attribute as hyperlinks that will open the target in a new window.
  - Links to glossary terms
    Special terms used in the body of DITA topics can be linked to their corresponding glossary entry definitions through the keyref feature, introduced in DITA 1.2.
  - Indirect linking with keys
    Indirect linking and referencing is a way of specifying the target of a link or reference in the ditamap, rather than in the topic. The feature was introduced in DITA 1.2. This allows links to have different destinations, depending upon the ditamap in which the topic is used.
- Cross-referencing elements in a topic
  Cross-references to elements within topics such as figures and tables allow a reader to easily navigate through a document, whether it is in a page layout format or a hypertext format. The xref element is always used for cross-referencing elements within a topic.
- Links in related-links sections
  When a topic requires cross-references to other topics where those cross-references will always be valid in the context of the topic, they should be contained within a related-links section after the topic body. In all other cases, cross-references should be defined in the relationship table of the ditamap.
- Managing cross-references
- Cross-references in titles
  You should not use cross-reference elements within topic titles.
Content re-use
Metadata, conditional processing, and indexing
The DITA documentation process
DITA authoring concepts
Moving from style-based authoring to a structured authoring methodology such as DITA requires a radically different approach to writing.

Format of href attribute in cross-references

The href attribute requires the address of the referenced resource to be in the standard URI format.

The resources being referenced in xref, link, lq, glossref, and source elements are specified in the href attribute.

A URI, or Uniform Resource Indicator, is a standard for referencing resources on the Internet. The similar term URL, or Uniform Resource Locator, means a specific type of URI where the location and the means of retrieving the resource are both incorporated in the address. For example, the URL http://store.scriptorium.com/items/Books/list.htm nominates the address of the resource and the protocol to use to retrieve it (in this case, http). In general, however, most people use the terms interchangeably!

Files on a file server or network drive on a local network can be referenced using the URI convention. Most DITA authoring tools will let you browse for the resource you want to reference, and then format the address in the correct UNC format. For example, the address of a file on a network server must be prefixed with the protocol smb://.

You must use (forward) slash characters for path separators. Do not use backslashes. Such file references are URIs in DITA, not file paths. The backslash is an illegal character in URIs. When referencing resources on a network server, prefix the UNC path with smb://.

You cannot use an ampersand (&) character in an href attribute. If the URL being referenced contains an ampersand character, the & character escape should be used to indicate that character.