validateNamespaces reports an undeclared prefix in a part root's
Ignorable as ignorable-undeclared, and the markup-compatibility
processor reports the same prefix as mce-unbound-prefix. Keep the
established code, once: one processor finding is dropped per
ignorable-undeclared on the same part and prefix (#309). A prefix only the
processor sees unbound (an Ignorable below the root, or a root prefix
bound only on a descendant) keeps its finding.
validateNamespacesreports an undeclared prefix in a part root'sIgnorableasignorable-undeclared, and the markup-compatibility processor reports the same prefix asmce-unbound-prefix. Keep the established code, once: one processor finding is dropped perignorable-undeclaredon the same part and prefix (#309). A prefix only the processor sees unbound (anIgnorablebelow the root, or a root prefix bound only on a descendant) keeps its finding.