The info in the PDF is just a brief part of the explanation. Use the URL on the top of the screen capture to read all of the info. The web site isn't mine, just something I found while doing research on mixing drivetrain parts.
Regarding the comment of problems with the Microshift & RD-7402, I wonder if they were trying to use a 7 sp shifter & RD-7402 with a 7 sp spaced cogset.