Page 185

Location: Chapter 19, Appendix

It is (fifth line of the Appendix)

... if it is built up from the letters $B$, $C$, $S$, $T$ and variables.

It should become

... if it is built up from the letters $B$, $C$, $S$, $I$ and variables.

Short explanation

Here, the presence of a $T$ where an $I$ is expected is clearly a typo.