Originally Posted by
jackal
Technically, the commas are an "or," so you're telling ITA: one single flight on United or United or United. (Not sure if the spaces after the commas affect the syntax, as I always do something like "UA,DL,AA"). The correct syntax is without a comma, as KVS indicates.
Spaces affect the semantics significantly, as they delimit legs! What SiberianTiger is actually asking: "one leg on United or(
comma) on nothing then(
space) one leg on United or(
comma) on nothing then(
space) one leg on United or(
comma) on nothing".
Which should actually work if ITA was smarter and accepted "nothing" as a valid input.