/*
   00 01 02 03 04 05 06 07 08 09 ->>> x
00 xx xx xx xx xx xx xx xx xx xx
01 xx                         xx
02 xx                         xx
03 xx                         xx
04 xx          18 1A xx       xx
05 xx          18 1B          xx
06 xx          19 1C          xx
07 xx                         xx
08 xx                         xx
09 xx                         xx
10 xx xx xx xx xx xx xx xx xx xx

^
^
|
y

switch (FEAT_INDUSTRIES, SELF, oil_rig_location_callback, industry_distance(INDUSTRYTYPE_OIL_RIG, -1) ) {
 0..6: CB_RESULT_LOCATION_DISALLOW;
 CB_RESULT_LOCATION_ALLOW;
}
*/