Purpose of error documents and the HTTP Status Codes they set or should set (error 404 etc.)

[eluser]Banana Man[/eluser]
Hi, could someone please me help clarify what the purpose of each of the documents is


1. error_404 = document not found, and it sets the appropriate header

Code:

<?php header("HTTP/1.1 404 Not Found"); ?>

2. error_db = connection to database has failed

there is no header set for this, would i be correct to add the following to the top of error_db.php ?

Code:

<?php header("HTTP/1.0 500 Internal Server Error"); ?>

3. error_general - is this error only shown when disallowed charaters are in the url, if so shouldn't this be renamed with this in mind and also have the following header ?

Code:

<?php header("HTTP/1.0 400 Bad Request"); ?>

4. error_php - should this have a header set ?


If anyone could shed some light on this, or offer any views on this topic of appropriate headers being sent, i'd appreciate it v much
Thanks