For those who are intrested...
In FF7, when you want to load and execute a new field file, you execute a JUMPMAP. The first two bytes are the field file you want and the other arguments look like an inital X,Y, and Z location of the PC.
There are about 750(ish) field files that JUMPMAP can call, but are refrenced by a number, not a filename. My theory is that somewhere in that big ball of bits is a sector look up to equate the jumpmap number with the top of the field file.
However, as PCs require a filename, as they can be placed anywhere on the disk. I found the lookup table in flevel.lpg The file is called "maplist" and has a sequenal list of the field files in order of the JUMPMAP argument.
I tweaked the maplist and will be posting it in the Q-gears froum, (where it was requested).
If you can find the JUMPMAP sector map for the PSX version, that would be great. I'm kind of broken in that respect as my CD-R can't mount a PSX disk properly.