Evolution of the ribbon PR and its hook PRH, based on manual tracing of the ribbon. Individual colors correspond to individual times, as is indicated. Pink and orange circles indicate two spatial positions of interest. The orange one is outside of the PRH at 00:30 UT, inside at 00:32 UT, and again outside at 00:36 UT. The pink one is first outside PRH, but is swept by the PRH at 00:36–00:40 UT (see text for details).