Some netdoc parser types don't accept UNRECOGNIZED items.

In our network document meta-format, unexpected items are generally accepted and ignored. But not every one of our SectionRules types actually behaves that way. For example, AUTHCERT_RULES does not permit the UNRECOGNIZED item type.

IMO this reflects a problem in the SectionRules API: The constructor of a SectionRules object should have to explicitly say so if they want to permit or reject unrecognized items.

This is an actual Bug.