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RedirectMatch 301 t(.*)$ /forum/showthread.php?t=$1
RedirectMatch 301 f(.*)/$ /forum/forumdisplay.php?f=$1
RedirectMatch 301 u(.*)/$ /forum/member.php?u=$1
RedirectMatch 301 sitemap(.*)/$ /forum/archive/$1
RedirectMatch 301 sitemap(.*).html$ /forum/archive/index.php$1.html