These are terms describing what happens to copper pipe when it is bent in a floor-standing pipe bender and you do not have the roller pressure adjustment correct.
If you have the roller (that presses on the guide bar) too loosely adjusted, the inside curve of the bent pipe develops 'ripples' or corrugations across the pipe. These are unsightly and also increase flow resistance in the bend -- which you do not want!
If you have the roller adjusted too tight, you get excessive 'throating' on the inside curve of the bend -- which is a flattening of the pipe by pressure from the former (the quadrant). You always get some throating whenever you bend a pipe in a bender (hand or floor standing), but if excessive it also increase flow resistance, and is therefore undesirable.
I came across these terms during my NVQ2 plumbing course a while ago. But you can see explanations in books like Treloar's "Plumbing Encyclopaedia" -- highly recommended.
