Imprecise referencing of normative material in conformance clause.
This "specification normatively defines ..V5.1 with a RELAX NG grammar and a set of Schematron assertions."
These Schematron assertions are nowhere to be found or referred to, when looking in the normative body of the specification.
The Schematron reference in section 1 is a general one. Same for the one in Normative ref sections. The material referred to in front-page just defines a work product parts - is not a valid way to refer to precise material needed for conformance.