Summary: you pick a waypoint (VOR or Intersection, etc.), the airway, then the exit waypoint for the airway. Hi and Lo airways (J/V) are both in the database, and are colored differently on the MFD. You can "collapse" the airway on the Flight Plan page so it shows the entire airway between the entry/exit point as a single "leg", or "expand" the airway to show all the individual points that make up that airway leg. DTK doesn't show if you collapse, as the airway might have a bend. The system doesn't warn you about airways that are unidirectional (few and far between) or that have limited operating hours (mostly international). It does some tricks to handle "reversing" a flight plan...
