By default there is no main caption but it can be set with -title=.
By default sub-titles are created from the name of the namespace or class ADOC is processing.
Currently there is no way to replace those defaults. In rare cases one wants to.
An example is ]CodeBrowser -???: this works on ⎕SE._CodeBrowser resulting in the title _CodeBrowser. A better title would be CodeBrowser of course.