XLink

XLink allows an element to behave like a hyperlink. It exists as a special namespace that should be declared in an ancestor element.
xlink:actuate specifies when the linked resource is read and shown. The valid values are ‘onLoad’, ‘onRequest’, ‘other’, and ‘none’.

xlink:href

specifies the URL of the resource.

xlink:show

specifies where to open the link. The valid values are ‘embed’, ‘new’, ‘replace’, ‘other’ and ‘none’.

xlink:type

specifies the type of the link. The valid values are ‘simple’, ‘extended’, ‘locator’, ‘arc’, ‘resource’, ‘title’, and ‘none’.

xlink:role, xlink:arcrole, and xlink:title

describe the meaning of the resources within the context of the link.

xlink:label, xlink:from, and xlink:to

are used for traversal.

XLink is not supported by browsers currently but other XML processors may use it.