Any rules about heel heights or boot modification?

[Query]

I'd like to know if the ISI, or United States Figure Skating (directly or through the ISU, has rules specifying a minimum heel height in skating boots or skates, or any other rules about boots, or if there rules about modifying boots (e.g., to reduce heel height).

I don't find anything about boots or skates by using a search engine on US Figure Skating's current website, though Rule 6037, 7037, 8027, 9027 mention blades, e.g.,

Skate blades: Figure skating blades used during competitions and tests (or hockey skate blades used during skating skills
tests or skating skills events at competitions) must be sharpened to produce a flat to concave cross section without change
to the width of the blade as measured between the two edges. However, a slight tapering or narrowing of the cross section
of the blade is permitted.

Nor have I found anything about boots or skates or blades on ISU's current website, except Rule 500 of the "General Technical Rules in single and pair skating and ice dance" on the ISU website.

Definition of the skate blade
Figure Skating blades used during competitions must be sharpened to
produce a flat to concave cross section without change to the width of the
blade as measured between the two edges. However, a slight tapering or
narrowing of the cross section of the blade is permitted.

(Interestingly, rather than referring to boots or skates, or to the use of blades on the ice, ISU technical rules refer to feet or edges or toe picks. E.g., rules about whether the "free foot can touch the ice".)

But perhaps there are rules about boots or skates in other publications, or in members-only websites? Or maybe I'm searching wrong?

Also does anyone know if there are heel height or boot modification rules for ISI (Ice Sports Industry) tests or events? (My ISI handbook is out of date.)