To have DITA2Go create trails of links, specify the following setting:
[Trails]
; MakeTrail = No (default) or Yes (enable use of <$_trail>)
MakeTrail=Yes
The default setting, MakeTrail=No, ensures that the overhead of collecting information to construct trails will not be imposed if you do not use this feature.
When MakeTrail=Yes, DITA2Go creates a trail for any heading (or other paragraph format) for which both of the following are true:
For both split and extracted files, and for the original file, predefined macro <$_trail> causes insertion of a trail according to the settings in [Trails]. The trail is always to the first paragraph in the file. DITA2Go inserts trails only if MakeTrail=Yes.