Mine

RewriteEngine On

RewriteRule     ^([^.]*).xml$   /get_xml/file/$1        [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule     ^([^.][^/]*)/   /$1\.php                [L]
RewriteRule     ^([^.]+)$       /$1\.php                [L]
RewriteRule     ^([^.]*)\.html  /$1\.php                [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !(.css|.js)$
RewriteRule     ^(.*)(.php)$    /error404_doc/$1/       [L]