Everything in context is correct that you said. This is a typo which should read...
Originally Posted by Doremus Scudder
My assessment of what Minor White was doing above was a bit unclear. He is obviously placing his shaded palm in Zone IV.
I have a hunch you are helping OP...
Here's a brief summary of what I based this on...
Minor White "Zone System Manual, How to Previsualize Your Pictures" outlines "Short Cut Exposure-Development Calculations"
1. Take a meter reading off the palm in shadow
2. Place on Zone IV to set exposure
3. Take a meter reading off palm in sun
4. Development determined by difference in the two readings.
5-Zone difference N-2
4-Zone difference N-1
3-Zone difference N
2-Zone difference N+1