What I call the triangle is called ID or I in the files. Normally these are the mesh of walkmesh.
http://wiki.qhimm.com/FF7/Field/WalkmeshFor example with a walkmesh with 3 triangles:
Number of Sectors= 3 triangles
Sector Pool:ID1= (x1, y1, z1, -) (x2, y2, z2, -) (x3, y3, z3, -)
ID2= (x1', y1', z1', -) (x2', y2', z2', -) (x3', y3', z3', -)
ID3= (x1'', y1'', z1'', -) (x2'', y2'', z2'', -) (x3'', y3'', z3'', -)
Sector Access Pool:AccessForID1 = (None, ID2, ID3)
AccessForID2 = (None, None, ID1)
AccessForID3 = (ID1, None, None)
With Makou you can't see the ID, but with the last version of Deling, it's possible.