My understanding of the JAR 1.405 is that it equals an app ban if the RVR is below prescribed limit (Normally 550m RVR for CAT I ILS).
Normally if the commander gets info that the RVR is below that minima, and he is above OM (or 1000 AGL) he must abandon the approach no later than the OM. However if he is inside the marker he can continue to the prescribed minima.
One note though. If I recall correctly there is no visibility in the 1.405. If one is given visibilty he can convert that to RVR which is almost always greater.