Mark, not really. The target points within the standard ZS are based on the ZS construct. The EI speed point is a good example. "0.1 above B+F", ie a target density, on its own doesn't contain much information about shadow tonality. It disregards the shape of toe, for example. It's just a rule of thumb, which is why ZS EIs change with variations in development. The fractional gradient speed, closely related to the first excellent print speed, is concerned with the gradient (ie contrast) at the speed point in relation to the total average gradient. This is a fundamental concept in the first excellent print and fractional gradient (0.3G) method - ie the speed is a means to getting sufficient toe contrast in relation to total contrast. This is different than targeting a fixed density for a speed point. It makes sense if you think about what determines local contrast and tonality in a print. A density on its own is meaningless without knowing the gradient at that point.