sorry to appear thick but what food does rmb stand for?

Raw Meaty Bones.
:)

How meaty is meaty ??

Not like the bones you get from the butcher, as far as I can work out, because they take every scrap of meat off.

I would class rmb's as pork-lamb ribs,chicken wings-necks,thighs,quarters...anything that the dog can totally consume,bone and all.
Recreational bones are the ones they cant totally consume,such as marrow bones,lamb shanks etc.