When Tiki generates a "page cannot be found" error
message, the "404 Not Found" header message isn't sent.
Instead, the regular "200 OK" is sent.
This causes robots (such as Google) and web proxies
respectively to archive or cache invalid pages. It
also prevents smart webclients and peers from
effectively managing bookmarks and links.
Example of .php file that incorrectly sends 200 OK:
(see the last if statement, towards the bottom of the file)