Searching for 'FreeBSD PORTREVISION and PORTEPOCH' (which is very close to the chapter title "5.2.3. PORTREVISION and PORTEPOCH") returns the old 4.5 documentation, and not 11.2. I think this has to do with the way how chapters are formatted, and the fact that chapters don't have individual links. 4.5 documentation was formatted better search-wise.
Fixed, sorry for the *big* delay and thanks to dbaio@ for fixing the problem!