(1) add binding content object to param/style/timing value verifier signature to permit verifying content object specific semantics;
(2) for completeness, add missing style value verifiers that are handled by schema validation, but may (at some point) need additional verification;
(3) move root extent verification out of semantics verifier and into extent style value verifier;
(4) add default parameter info (not yet used);
(5) add default (initial) style property info (not yet used);