Originally Posted by VPescado
This information must be available programatically? Where else does expedia get it. Actually any booking engine needs to have this info for fare construction.
Booking engines aren't necessarily always exact.
In some cases, I've seen booking engines breaking fare rules.
For example, when I was quoting out UA fare between LAX and SYD last May, expedia.com has shown invalid routing via SBP with flight number 7XXX.
The fare only allowed 1~1699 for flights.
Honestly I'm not sure how expedia.com sets up routing parsers, but ITA rarely shows different routings from what expedia.com shows.