To specify map levels for topics, assign a level number to each format that you map to a <title> element at the topic level in [DITAParaTags]; see §24.4.3 Mapping paragraph formats to DITA block elements. For example:
[DITAMapLevels] ; para format = level of topics it starts in ditamap, default 1. Heading1 = 1 Heading2 = 2
Each instance of a paragraph format assigned a level number generates a <topicref> that nests the lower <topicref> elements. For paragraph formats that are not listed here, but that are mapped to <title> elements at the topic level in [DITAParaTags], DITA2Go uses any level assignments you have provided for those formats in [HelpContentsLevels]. See §16.4.3 Setting contents levels for HTML-based Help.
If you direct DITA2Go to nest topics, DITA2Go adjusts map levels as follows:
Any adjustments to map levels also affect the chapter ditamap.