Tokenized (non-CDATA) attribute values normalize before validity
checks, so enumerations, NOTATION lists, and the ID/IDREF table see
collapsed values. External parsed entities lose their leading text
declaration (validated: version optional, encoding required, never
standalone) instead of carrying it into replacement text. Character
references in PE literals expand at declaration time, making the
Appendix D '%zz;' example parse. A PI target inside the DTD subset
must be separated from its data. Sun baselines tighten to not-wf 55/56
and valid 26/28; the two remaining valid failures share one cause
(replacement text with markup is included as character data, filed
separately).