Architectural specification : Architectural Specification: Base : DITA processing : DITA linking : Links within topics
   
Links within topics
A topic may contain several types of links.
Content reference links from any element in the topic that allows @conref or @conkeyref.
Related information links, within a <related-links> element following the topic body. The related links are usually rendered at the end of the topic.
Image links created using <image>. Image elements may use <longdescref> to link to the long description for the image as a supplement to the <alt> element.
Object links created using <object>. Object elements may use <longdescref> to link to the long description for the object as a supplement to the <alt> element.
Navigation links created using <xref>. For output media that support hyperlinking, the <xref> should result in a hyperlink.
Navigation links created using @keyref on elements that allow @keyref but not @href (e.g., <ph>, <cite>, <keyword>, and <term>).
Metadata associations using <data-about> in contexts where <data> is allowed.
Navigation links from long quotes to the source of the quote using <longquoteref>.
Links to resources outside a topic's containing XML document that use direct URI-based addresses establish unconditional topic-to-resource dependencies. Such dependencies can impede reuse in two ways:
The linking topic cannot be used in a given map unless the dependent resource is also used.
The linked resource cannot be dynamically changed based on the map context in which the linking topic is used.
These issues can be avoided by using key-based addressing. Because keys are defined in maps, each map that uses the linking topic can bind the key to the most appropriate resource.