By default, DITA2Go treats all <topichead> elements as title-only topics, so they behave the same in generating content (their navtitle) in both HTML and print (RTF) output. This is also true for other topic heads derived from <topicref> that do not have an href attribute, where the title is the <navtitle> and the <shortdesc> element is in <topicmeta>.
To turn this behavior off and include such topic titles only in the TOC:
[TopicHeads]
; TreatTopicheadsAsTopics = Yes (default, treat topicheads as topics
; or No (include them in the TOC only).
TreatTopicheadsAsTopics = No
To specify a root element and ID base name for title-only topics:
[TopicHeads]
; TitleOnlyTopicType = root element to use for virtual topics that are
; generated from topicheads, any topic root; default "topic"
TitleOnlyTopicType = topic
; TitleOnlyTopicID = base name for @id for virtual generated topics,
; to which a sequence number 1..n is added; default "head"
TitleOnlyTopicID = head