I recently found a roll of Super-XX negatives in my grandfather's house. These negatives were very bizarre. The film was normal 35mm, but it had "BH" style movie sprocket holes (outward curving sides). The film itself had normal frame numbers (1,2,3, etc), and it was a negative film. Does anyone have any clue why this was? Were all 35mm films sprocketed this way "back in the day"?