thank u guys
All useful answers.
Nick wrote
Whatever is reported has to be within limits, if they report only touchdown then that is all that is required. I believe that (not certain) to have a CAT III system approved you need to have multiple RVR reporting systems (certainly required for 125M TO).
There are a few weird places, RIX being one, where they used to have a CAT III ILS and therefore MRVR but since downgraded to CAT I but still give you all three on approach in poor weather. As they report all three you must have 550/125/75.
Which is just what I "suspected". Whatever they give you, you must comply with. What I would like to see is in what document it is stated the relation between a runways Cat 1,2 and 3 capability and the number of reported RVRs. For instance: is it required to have the 3 RVRs for cat 3?
Thanks 172 and 747, as well. In fact, in my airline the MID RVR requirements are different
I was aware of the 60 kt rule, which rises a few questions of its own, like how it is computed, etc... Some say that you can land in a 300/250/<50 if you select a high autobrake setting so that the SE RVR becomes irrelevant.