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In 4.3.1.1, it is explicitly asserted "If {fixed} is true, then types for which the current type is the {base type definition} cannot specify a value for length other than {value}." In the case of length, this is true regardless of whether {fixed} is true of false. This makes the unadorned sentence seem a bit odd--conclusion true regardless of the truth of the hypothesis. Perhaps a mention of why this is true but unusual would be in order.
A wording proposal intended to resolve this issue among others was sent to the WG 27 February 2008: http://www.w3.org/XML/Group/2004/06/xmlschema-2/datatypes.omni200802.xml (member-only link).
At its telcon today, the XML Schema WG adopted the wording proposal at http://www.w3.org/XML/Group/2004/06/xmlschema-2/datatypes.omni200802.xml (member-only link), and believes this issue now to be resolved. Since the originator is a WG member and was present on the call, it seems likely that you agree that the issue is successfully resolved. Still, please so indicate by changing the status of the bug report to CLOSED. Or reopen it if you discover a snag. Silence will be taken to mean consent.