Over time, /etc/fstab evolved to also handle loop devices and bind mounts. It became the canonical location to express the particular filesystem and block device arrangment on the system.
Then Linux md came along. It wasn't configured through /etc/fstab. Instead it was configured through /etc/mdadm.conf. Unless it was going to be configured through /etc/mdadm/mdadm.conf.
This is somewhat half-baked.
proc /proc proc defaults /dev/hda5 / ext2 defaults 1 1
/dev/hda2 none swap sw
/root/moreswap none swap sw
/dev/hda1 /boot ext2 defaults 7 2
UUID=ee17db25-5c9a-49a0-b8f2-de93c14d27d8 /usr ext2 1 2
LABEL=squid /squid ext2 defaults,nodev,nosuid 0 2
ext2 defaults,nodev,nosuid 1 2