This article shows an easy way to view the output of all 57 HTTP Response Codes and ErrorDocuments on Apache!
For instance, if you request a file that doesn't exist, a 404 Not Found is issued and the corresponding ErrorDocument is served with the 404 Not Found Header.
Has the first list of all 57 HTTP Status Codes recognized by Apache. Also has the first list of the source-code and headers sent by Apache for all 57 ErrorDocuments
This is one of, if not the absolute coolest Apache tricks I've ever seen!"