Split SECTION regexp to multiple lines. It can't use (?x) because it is pasted into the middle of other regexps.
linkify "clause 10.1.1" even though that is probably an editorial mistake
Change uses of xref_re to use re.sub, fixing a horrible bug that just happened not to bite in the document as it is. Who wrote this junk? (it was me)
Change fixup_links to strip out more Word macro drool.
Common up the various regexps that match Word REF macro spam.
Tweak a few link regexps to cope with the consequences of using a more permissive REF regexp in some places.