1.2. A step into the future

TYPO3 4.0 provided a 'hidden/undocumented' feature that lets you define your own 404 page as a file or URL using configuration settings ([FE][pageNotFound_handling] = /404/). One option is to create a "static" HTML file, set the path to it in the configuration, prepending it by "READFILE:", and TYPO3 will show it as 404 page. However static files are not good. You cannot display, for example, an automatically updated site map with it. Here URLs come to play. If you set a URL (relative or absolute) for pageNotFound_handling, TYPO3 will fetch it and display it as the 404 page.  The problem with this solution is that TYPO3 (3.x and 4.0) redirected you to this 404 page. Technically this means that a search engine like Google was not able to recognize this as a 404. So it would never remove this page from it's database. Also the HTTP error codes section from your statistics program like AWStats would never indicate that you have missing pages on your website.