Take a specific example: jumps. As far as I can tell they are not fully described in any USFSA documents.
E.g.,
http://www.usfigureskating.org/New_Judging.asp?id=361 has online copies of the USFSA Rulebook. The Rulebook's "List of Jumps" table says which edges and rotation directions are involved, and the Glossary at
http://www.usfsa.org/About.asp?id=60 (
neat link) says whether the jump and landing are on the same foot or not, but nothing is said about body positions and motions, or about what must be done before the jump edge, or after the landing edge, if there are such requirements.
(The UFSA Basic Skills Instructors Manual describes a number of half-rotation jumps, as executed at Basic Skills test levels. It is not said that these are to be extrapolated to higher rotation jumps, to be used as test and competition standards. In any event, little is said about body positions and motions.)
Various USFSA pages have general comments for judging jumps in general, but don't describe individual jumps.
Or are the jumps are instead fully described in ISU documents (where?), and the USFSA accepts those standards unmodified, for both tests and competitions?
Or has the USFSA indeed relied on the PSA to describe things they consider too basic to explain, which would mean they effectively let the PSA set some of the USFSA test and competition standards?