Yop:
The path that I'm following here is trying to answer the OP original question, and explain which inspectors enforce support here.
Specs are written by Arch/EE and have to be complied with providing they are either 'to code' or greater. Mfg specs/instructions are mandatory under 110.3 (B).
Yes, I agree with you....I refer to the NEC Handbook and the commentary often. Most, if not all of that is easier to grasp, and assist all of us. I use the Handbook in the NEC class I teach. I have the NFPA Handbook, and right now I can't tell you who wrote the commentary. I also refer to Mike Holt's books, and his commentary.
