Originally Posted by
serfty
3 Continent is also possible NA-ASIA-SWP-NA or vv; see pandaperth's post #9.
Also possible is SA-NA-ASIA-xNA-SA or variants thereof
Edited to add: Oops - the above starts and ends in SA, which means 'a minimum of a four continent fare'
Possible 3-continent fares begin and end in ASIA or NA, such as:
ASIA-xNA-SA-NA-ASIA or NA-SA-xNA-ASIA-NA
What makes such routings possible are the DEL-ORD flight and the rule which allows a second (transitory) entry to NA.