(topic mapgroup-d) The %topicref-atts-without-format; parameter entity represents a group of attributes used in numerous map elements: mapref, and topicgroup. The set is similar to those documented in topicref-atts but excludes the format attribute. 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. 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 <anchorref> specializes <topicref> to set format="ditamap" and type="anchor" defaults for a reference to an <anchor> to enable push of collections of content smaller than a map onto an anchor. The <anchorref> specializes <topicref> to set a format="ditamap" default for more intuitive map references The <topicset> specializes <topicref> to set a chunk="to-navigation" default and required id attribute to make it easy to delimit standalone, reusable collections of content within a map (such as lessons within a course or large tasks explained by a collection of discrete task topics). The <topicsetref> pecializes <topicref> to set format="ditamap" and type="branch" defaults for a reference to a <topicset> to enable reuse of small collections within a map (especially for task composition approaches in which multiple larger task collections reuse smaller component task collections). The <keydef> specializes <topicref> to set a chunk="to-navigation" default and required id attribute to make it easy to delimit standalone, reusable collections of content within a map (such as lessons within a course or large tasks explained by a collection of discrete task topics).