Is the appendix in the back of NFPA 72 part of the enforceable code?

No.
The appendix and FPN's in any NFPA standard/code are not enforceable. Some AHJ's use it as reference if the code is not clear, but is not technically enforceable.

Last paragraph of 90.3 (2002) "Annexes are not part of the requirements of this Code but are included for informational purposes only."