Panels a)−c): AIA 131 Å images showing a sigmoid flux rope proxy on 2013 August 14. The yellow, red and blue dotted curves in panels a)−c) delineate the fine structures of the rope proxy. Panels d)−f): corresponding AIA 304 Å and 171 Å images and HMI magnetogram. The three colored curves in panel f) are the same as the dotted curves in panels a)–c). An animation (movie7.mp4) of the 131 Å channel shown in this figure is available online.