textpattern/textpattern-forum/master/public/api/.htaccess

<ifModule mod_headers.c>
    Header unset X-XSS-Protection
    Header unset X-Frame-Options
    Header unset X-Content-Type-Options
    Header unset Expires
    Header unset Cache-Control
    Header unset Pragma
    Header unset Content-Security-Policy
</ifModule>

<IfModule mod_rewrite.c>
    RewriteEngine On
    RewriteRule ^topics/([0-9]+) index.php?action=feed&fid=$1 [QSA]
    RewriteRule ^posts/([0-9]+) index.php?action=feed&tid=$1 [QSA]
</IfModule>