"Steven P. McNicoll" wrote:
The AIM hasn't any force, legal or otherwise.

I'm not a lawyer and don't play one on TV, but:

Federal Aviation Regulations do reference the Aeronautical Information
Manual (AIM), and I would presume that therefore the content so referenced
makes the knowledge "official" and legal for certain purposes.

For example, in section 61.65, Instrument rating requirements:

"(b) Aeronautical knowledge. A person who applies for an instrument rating
must have received and logged ground training from an authorized instructor
or accomplished a home-study course on the following aeronautical knowledge
areas that apply to the instrument rating sought:

(1) Federal Aviation Regulations of this chapter that apply to flight
operations under IFR;

(2) Appropriate information that applies to flight operations under IFR in
the "Aeronautical Information Manual;
.....
"

AIM is likewise mentioned under sections 61.97 and 61.105.