As I recommended in DITA: Specializations (task, concept, reference)?, author in the base topic type. You won't find yourself doing acrobatics to combine topics. However, you may want to combine topics in order to create nested subheadings.
Combining topics with the chunk attribute
chunk="to-content" attribute allows you to merge child topics into a
parent topic in your navigation. You add the
chunk attribute on a
If you want the child topics to actually appear in the table of contents, use the "yes" value.
Although the chunk attribute works easily enough in the TOC area, it's problematic with linking. Chunking creates issues with relationship tables. (See DITA: Limitations with the chunk=”to-content” attribute in relationship tables.)
Combining topics by nesting elements
A better way to combine topics is by nesting elements. When you nest elements, you add
conbody elements inside each
other. Here's an example of how nest task elements.
With nesting concepts, here's what that looks like
Basically, just bookend the individual
concept elements inside one
concept element that functions as a container.
Using an outputclass for a third-level section
You can also "cheat" to
combine topics against the design of the DITA structure by crafting an
outputclass attribute to look like a third-level heading: like
p.level3 class to the webhelp stylesheet. Assuming your
OxygenXML install directory begins in your /Applications
folder, the path would be as follows:
Open the webhelp_topic.css file, scroll down to the bottom, and add something like this for your style:
This is more of a workaround hack than any good technique. Sometimes you just need a third-level heading, though, and this works.