Options +FollowSymlinks

RewriteEngine on

RewriteRule ^([a-z0-9_\-]*-(f|all)[0-9]+(p[0-9]+|/index[0-9]*)?\.html)$ forumdisplay.php/$1 [QSA,L]

RewriteRule ^([a-z0-9_\-]*-(t|p)[0-9]+(p[0-9]+|/index[0-9]*)?\.html)$ showthread.php/$1 [QSA,L]

RewriteCond %{REQUEST_URI} !(index\.php|\.css) [NC]

RewriteRule ^(archive|sitemap)/(.*)$ $1/index.php/$2 [QSA,L]