The solid lines are the major trendlines, created like we normally do using the first peak and a following one.
The dotted lines however, are lines I've been drawing for a while that I call sub-trendlines (haven't really seen em anywhere else).
They are all drawn the same way, by using a peak before the move to the ATH/local high and a peak after it, as shown by the arrows and the (0) example.
I've noticed that very often they serve as big s/r targets within the major trend.
What do you think?