Hmmm. Never seen this before.

Flying SFO-MEL next week. This is a 747-400 which has
a 3-4-3 seating. E+ has people distributed throughout
the E+ seats.

However, on the return on Dec 10th both MEL-SYD
and SYD-SFO has the entire central column of
seats in E+ (i.e. the 4) booked! But there are plenty
of seats in the two 3 areas. What's up with that?
Is than indicative of a group booking.