FAT2e Chapter 25, Page 627: Textbook,
The last paragraph refers to "Figure 25-18". It refers to the reverse boost valve. Figure 25-18 is located on page 633 and is not an image of the reverse boost valve, but rather a shift valve. Figure 25-18 it is called out again on page 632 as a shift valve.
Also appears in the E-Book, Figure 25-18
FATO Chapter 25, LO K25001: it refers to Figure 17 which is not a reverse boost valve, but an image of a shift valve, Figure 17 is called out again under the topic heading "shift valves".
Note: I do not see an image of a reverse boost valve.