Read this while reading on Auto land (Oxford).
The auto land weather requirement for a CAT I approach is : "Decision Height should be no lower than 200ft, and with either a visibility of no less than 800m or an RVR of no less than 550m."
So, my guess is when both RVR and VIS are stated on the approach plate. As long as you satisfy one of the two requirements you can continue the approach to land. So a few people who said it before I did were right. Again, I'm only guessing.
Any counter on this?