Panels a)−c): AIA 131 Å images showing a sigmoid flux rope proxy on 2013 November 11. The red curve S1 in panel b) denotes a sigmoid structure. The blue curve S2 in panel c) outlines another sigmoid structure, and the red dotted curve S1 duplicates curve S1 in panel b). Panels d)−f): corresponding AIA 304 Å and 171 Å images and HMI magnetogram. The red and blue curves in panel f) delineate the duplicates of curves S1 and S2 in panel c). An animation (movie6.mp4) of the 131 Å channel shown in this figure is available online.