[Frontline]
Thats where the Frontline starts on the map - represented by a red line usually. I think startshow and endshow just define the visible points from the front line coords
[Routes]
single missions (and campaigns) use these coordinates to place moving trucks and ships - you can just define your own points - you can add shipping routes also
i.e.
[Route008]
RouteType=SHIPPING
StartArea=Mosak <----name from _targets
EndArea=Al'Duhok <----name from _targets
RoutePosition[001]=472000,486000
RoutePosition[002]=472000,498000
RoutePosition[003]=446000,538000
RoutePosition[004]=422000,552000
To work out the coords - ideally a mission editor is the best thing