OpenBSD allows partitions a-p ( 16 for the whole disk). FreeBSD disklabel allows 8 labels (a-h) for a slice (MBR partition).
For a fine grained partition scheme, needing more then the 8 labels of which 3 (a, b and c), already have been taken, your only resort is too use a second slice (MBR partition).
For one of my favorite partition schemes on FreeBSD I have to use a second slice:
- s1a: root
- s1b: swap
- s1c: reserved for the whole FBSD slice
- s1d: /usr
- s1e: /usr/ports
- s1f: /home
- s1:/tmp
- s1:h:/var/tmp
- s2a:/var
- s2b: /iso
Of course with the new FBSD gpt partition scheme this limit will be things of the past
