[TUHS] Partition table rationales?

Is there any information on the rationales behind the sizes and positions of the hardcoded partitions in the rp/hp drivers in V6? There are odd gaps of unused space between ones that appear to be intended to be used together (I think I have some pieces of the puzzle worked out below, but not all). For the rp driver, only rp[01] uses the whole disk - rp2 and rp3 are 9200 blocks. The hp partitions looked more complicated, but it looks like the manpage is wrong about where partition 2 starts - 84018 vs 48018. Partitions 0123 are 161584 blocks, 4567 are 162400 blocks. 4567 start on 100-cylinder boundaries, but are only a bit over 97 cylinders long - in fact, they are the same length as rp[01]: 203 RP03 cylinders. rp6 and rp7 are not mentioned in the manpage, and are 15600 blocks, making rp[65] and 47 reasonably non-wasteful configurations. Is there something special about 9200 blocks? rp2 and rp3 are that size, and hp1 is that size rounded to the next cylinder. V7 is much simpler: rp0 is the whole disk, 123 is a non-overlapping set with no wasted space. hp[0145], 016, and 017 are non-overlapping sets.