Bob Gardner wrote:

With reference to using Mode C as a defacto report....

5-5-6 Exceptions
{New-2003-15 a. revised August 7, 2003}
a. Do not use Mode C to effect vertical separation with an aircraft on a
cruise clearance, contact approach, or as specified in paragraph 5-15-4,
System Requirements, subparagraph e and f.

Maybe not right on point, but a suggestion that controller's do not
necessarily buy a Mode C readout all the time.

That book has rules then it has rules.