Does the restriction on Deprecated MathML cause retroactive content breakage? #2118
Description
In the section on MathML restrictions
EPUB Creators MUST NOT include elements and attributes marked as deprecated in [MATHML3] within MathML markup in XHTML Content Documents.
Does this mean, in this era of living standards, that as MathML adds items to the deprecated list existing EPUB content is retroactively made non-conforming?