For PAL pulldown, 12 frames of progressive input become 25 fields of interlaced output. This means that out of every 12 input frames, 11 contribute to exactly 2 output fields, and 1 contributes to 3 output fields.
One example might be the following list of output field pairs where the 6th input frame is used 3 times:
There are actually 25 cadence possibilities for 25i, as compared to only 5 in the NTSC 30i case. It is too awkward to refer to these cadences in the same way as for NTSC, for example: WSSSSSSSSSSSSWWWWWWWWWWWW. Therefore, the 25 cadences have been labeled 1 to 25 in the Cadence drop-down menu where the number indicates the index of the split frame that follows a whole frame.
