Originally Posted by
catharsis
Just to clarify - the word 'Nested' (at least in my mind) implies two separate tickets.
....so CAI-LHR-DUB//[DUB-LHR-DUB]//DUB-JFK-LAX-HNL (with the segments inside parantheses on a separate ticket) is a perfectly valid routing (I know as I recently flew it) and you are not 'discarding' 40 TPS,
you are wasting one extra segment comparing
to
cai lhr, dub lhr jfk lax hnl which is allowed by the routing rule.
and
the positioning involved only one-way instead of a round trip.