They have something to do with if they are available to buy at that particular base. For example
marketgood = gf1_package, 0, -1, 0, 0, 1, 1, 1
the first 0 = purchase level of 0 required (you can buy it as soon as you start the game)
marketgood = gf1_package, 0, 1, 1, 1, 0, 0, 1
The one above I am pretty sure means you can buy it from that base. I dont understand them fully but if you notice that only 3 of the ships in a base have 1 set of combination whereas the rest have different ones. Like I said Im no expert but from my mod work with the Babylon5 server with
TFK Killermatrix I noticed little things like that
Its better to die on your feet, than to live on your knees.