Nicholas: I have read and reread the following and I admit to not being completely able to understand what you are saying.
<It is easy to control local contrast with the negative contrast index in stops of scene luminance to stops of negative density and the paper contrast in stops of negative density (the same thing as stops of paper exposure) to stops of print luminance.>
Reading assignment: Meese,
The Theory of the Photographic Process, revised edition 1954, Chapter 5. Quiz on Friday.
On page 162 he plots the typical 'S' HD curve and along with it the curve of the derivative of density to exposure dD/dE. The derivative is the local contrast of the film or paper and is the change in negative density for a given change in scene illumination.
If one stylizes the HD curve as a perfect 'S' it turns out that the curve of local contrast is a bell-shaped curve reminiscent of a standard distribution.
Although people talk of a straight-line portion of the HD curve, in reality the HD curve hasn't got a flat spot on it. Ditto the local contrast curve. The local contrast changes throughout.
Plot the local contrast for a VC paper and you are in for a shock, an application note on this is in process and will be posted on the DA web site in the next few weeks.
That asside, a decent approximation can be had by confining oneself to the standard Zones. At each zone the constant change in exposure results in a different change in negative density or print reflectance.
If you have information on the film's response and on the paper's response (available in the Darkroom Automation 'Paper Seed Charts') you can transfer the range in scene illuminance to the range in print tone.
As an example:
You are taking a picture of a snow scene where the interest is in the shadows on the snow.
Metering the bright snow and the shadowed snow you measure a 1 stop difference.
In the highlight zones you know the film (from your prior testing) produces a 0.3 stop change in density for a one stop change in exposure.
Unfortunately, the VC paper you want to use also has low contrast in the highlights of, again, about a 0.3 stop change in print tone for a 1 stop change in exposure.
As a result the one stop change in scene brightness becomes a 0.3 stop change in the negative which then becomes a 0.1 stop change in the print tone.
Obviously, this isn't going to work - well it will work, producing the same disappointing snow scene you have been battling with all your life.
The solution is to move the 1 stop difference in snow brightness to the middle of the film curve where the local contrast is at it's highest by placing the snow where zone VI would normally sit at a local contrast of 1.2 stops/stop. By increasing development time, safe to do as the highlights are down on the curve, you can get a local contrast of 1.6 stops/stop.
By going from a VC paper which has very low highlight contrast to a graded paper you can get a local contrast in the highlights of .6 stops/stop by printing the highlights down a bit.
The resulting contrast in the print will then be 1.6 * .6 = 1 stop.
So the snow scene you metered at 1 stop of contrast will have a 1 stop contrast range in the print and look as pretty as it did in real life.
Shadow detail will be a problem, of course, so you may want to reflect light into the interesting shadows if you can and think about using a dilute developer to help bring up the shadows.
The highlights may lack a bit of sparkle because they have been printed down, and you will probably have to use an overall slight bleaching in a cutting dilution of Farmer's Reducer.
If you had to do the above using conventional OD units for negative and print density you will be forever converting from OD to stops of exposure and back again.
By using stops throughout, stops of scene brightness can translate directly to stops of print brightness.
Disclamer: All the numbers above are from the top of my head (or pulled from my ....) and are for illustrative purposes only.