I read Les' post with great interest as I sometimes do place my shadows on Zone IV. However, my thinking was not from how my meter might respond to different colors of light. Typically I think of shadows belonging on zone III. However, my goal behind exposing any negative is to assure that all of the important detail is recorded on the negative. Thus, a bit of over exposure and over development will be okay. This really all comes back to the old adage: expose for the shadows, develop for the highlights.