Errata, validating processors: Omission of reference to ”at user option” in section 5.2
Section 5.2 on ”Using XML Processors” begins like so: 
”The behavior of a validating XML processor is highly
predictable; it must read every piece of a document
and report all well-formedness and validity violations.”
Error: The sentences fails to refer to the obligation to
”report all […] validity violations” as an
’at user option’ requirement.
Replace: ”and validity violations”
With: ”and, at user option, all validity violations”
Delete: ”and validity violations”
Add: ”At user option, they must also report all validity
Recommended additional fix:
Replace the word ”must” with e.g. ”has to” or ”is obligated
to”, in order to to stronger reflect that the sentence is a
reference to things stated elsewhere in XML 1.0. Avoid seeming
to define same issue twice.
* That the requirements to report all validity violations is an
”at user option” requirement, is defined in the definition
found in section 5.1.
* The requirement that all ’at user option’ features MUST be
possible to enable and disable, is defined in the ’at user