Perhaps someone can clarify a point for me. We had an ATCO from Benson give a talk for a PFA strut years ago who said that the reason that they often can't provide either RIS or RAS cover is the zone of separation required is greater than that required for FIS. Therefore in a given block of air space only a certain number of RIS or RAS movements can be handled. FIS allows more movements through the same area. Am I right in thinking that FIS applies VFR separation rules whilst RIS and RAS use IFR separations?