A nicely put technical point Trev ! the wrath of RGS owners will descend rapidly methinks. In the meantime I've checked with an ex work mate who has over 30 yrs experience in General branch insurance and his view point would be that provided documents could be shown showing the frame as a RGS and has that would be the reason why an enhanced valuation would be expected by the owner in the event of a claim , then it should be described as an RGS . He also mentioned that some insurance companies but not all,specalising in "classics" still have experienced people to whom this type quiery could raised.Hope that is of some help ,BobH.