Marathon conditioning phase:
I'm not quite sure what your question is... I guess HRE answered it anyways???
Lydiard was inspired to come to his training program mainly by two things; (1) when he started running marathons, his track times improved, and (2) even though he ran more than anybody else and he was basically fitter than anybody else, he got beaten by others because he wasn't peaking correctly.
For (1), he figured, if it's good for me, it's good for others. He experimented on others; they started running more than ever before, basically like a marathon runner, and they got faster than ever before in the shorter distacnes. So he figured, that works!
When asked about the training mileage depending on the racing distance, Lydiard used to say that it (racing distance) doesn't matter; whether you are an 800m runner or a marathon runner, they both need high oxygen uptake level; so they all trained together during a certain perioed of their training.
As far as terminology is concerned, as I said somewhere before, Arthur sucked at terminology. We (=Foundation) will try to clarify that as well. As long as you understand what you need to do and why you're doing it, you'll be fine.