Map group elements
The mapgroup domain elements represent particular containment strategies within a set of topicrefs in a map.
The <topicgroup> element is for creating
groups of <topicref> elements without affecting the
hierarchy, as opposed to nested <topicref> elements
within a <topicref>, which does imply a structural hierarchy.
It is typically used outside a hierarchy to identify groups for linking without
affecting the resulting toc/navigation output.
The <topichead> element provides a title-only
entry in a navigation map, as an alternative to the fully-linked title provided
by the <topicref> element.
OASIS DITA Language Specification v1.0 -- 09 May 2005
Copyright (c) OASIS Open 2005. All Rights Reserved.