This complex spot group had six GOES class-X flares - this X3.1 was the strongest on Oct 24. The blue outline X-X' and Y-Y' is from SDO HMI magnetogram - it suggests the inversion line between opposite polarities within the group. Notice the small cluster of 'red' spots within the dominant 'violet' spot - and how the inversion line winds around them! The peak of this flare (X3.1) was missed - here we see it ~40m later: X1.1. Perhaps the flare arose along the N and W sides of line Y-Y', as the brightest ribbon spread well to the S of the group. Rumor suggests there were no CME's from this group? Yet the disruption of coronal fields and the ejection of a filament (i.e. mass) precedes all flares? Doesn't it?