The first paragraph on page 47 SHOULD read:
"The format options for 3.5-inch disks are 800K 2:1, 800K 4:1, and 400K 2:1. 800K and 400K refer to the capacity. 2:1 and 4:1 refer to different layouts of tracks and sectors on a disk. Choose 800K 2:1 for ProDOS 16 or GS/OS files and 800K 4:1 for ProDOS 8 files (or for a combination of ProDOS 8 and Macintosh files). The only time you should choose 400K is if you're using a single-sided 3.5" disk. The format option for 5.25-inch disk is 140K."
The essential (and correct) information in the new paragraph is:
When using ProDOS 8, select a 4:1 layout and ProDOS 16 and GS/OS should use a 2:1 layout.