The Proposed Update UTS #37: Ideographic Variation Database is available for review.
The purpose of the proposed update is to clarify the conditions under which a glyphic subset is appropriate for a given base character.
The proposed text uses a somewhat lenient criteria ("reasonable possible rendering"), and points to the unification rules for a possible way of verifying whether the criteria is satisfied but does not impose to stay within the confine of those rules.
An alternative is to strengthen the criteria and require that each shape in the glyphic subset be unifiable with the base character. A wording for this alternative is:
Stated another way, this implies that all the shapes in the glyphic subset must be unifiable with the base character of that IVS; for more information on the unification rules for Han ideographs, see...
and the example would be changed to indicate that the example glyph is not an appropriate rendering of U+5046, but is for the z-variant U+4FF1.