apache-upgrading.xml has a broken link to chapter n°4 ("Supported USE flags in 2.2.6-r4 and above"): line 194-195 <uri link="#use"> would be <uri link="#use-2.2.6-r4"> (or rather "use-pre-2.2.6-r4"? I'm not absolutely sure... Which is the right chapter? :P )
Fixed in CVS.