Shlepzig: I think we're largely in agreement - it seems that you're with me in saying that ROW begins when the arm starts extending (both in flick and traditional thrust), and that there are plenty of times when neither party has asserted ROW.
Following stickler tendencies like James, I'll point out that "absence of blade" is an overloaded term used for two very different things. Traditionally that described a standard attack without a blade taking, such as attack by disengage but no beat, and it is now also used to describe an "aggressive action" (I can't bring myself to say "attack") with the arm withdrawn.
CvilleFencer: You're right, I'm having difficulty visualizing this. When you say "Fencer A's hand goes to his 4 position" (or 6 position) after beginning to extend, are you saying he bent his arm (in which case I would say he lost ROW) or that he moved his bell laterally to close either 6 or 4 line while maintaining extension? (In this case I would say he retained attack but it would look weird....)
As shlepzig said, a good discussion. We've been at it a week and no flames or name calling. How can this be?
