RewriteRule ^forum/tags-(.*).html$ forum/search.php?search=$1 [L]
RewriteRule ^forum/tags-(.*).html_p(.*)$ forum/search.php?search=$1&page=$2 [L]
RewriteRule ^forum/tags-(.*).html_t1_p(.*)$ forum/search.php?search=$1&t=1&page=$2 [L]
RewriteRule ^forum/tags-(.*).html_t1$ forum/search.php?search=$1&t=1 [L]