Look at it as the higher of the published minimums or what your airline/aircraft is authorized to land with. My current equipment (744/8, three autopilots) considers CAT II as fail passive and CAT III as fail operational. We are approved down to a DH of 100 feet and 1000 RVR for a CAT II and an Alert height of 100 feet and 300 RVR for CAT III. So we would fall under the CAT II SA 1000 RVR. Since that approach requires 600 RVR for CAT III that would limit us even though our OpSpecs says we can land with 300 RVR CAT III.