This is an archived snapshot of W3C's public bugzilla bug tracker, decommissioned in April 2019. Please see the home page for more details.
Section 7 says: Polyglot markup surrounds attribute values by either single quotation marks or by double quotation marks. Those two occurrences of "by" need to be "with" (values can be surrounded by quotation marks, or markup can surround value with quotation marks, but markup can't surround them by quotation marks; that doesn't make sense grammatically (mixing passive and active voice, or something like that)).
Fixed in the editors draft. Thanks!