Thread:Project:Support desk/Strange reserved name issue when updating/saving pages, results in 500 server error/reply (3)

Umm good question, I'm not sure how to check if you have that installed. The obvious way it to look in httpd.conf, but from your description it sounds like you don't have access to that.

Some configs of apache will list what modules are installed in the http server header, as well as in error pages (for example the default 404 error page). But the type of people to install mod_security, are probably also paranoid and remove that sort of info. You might be able to do it with the php apache_get_modules function, I've never tried it (If one can indeed do that, we should perhaps add a check in the installer)

If you have access to the apache error_log, there might be entries corresponding to things prevented by mod_security (However its also possible your web host uses a filtering system that is similar to mod_security, but a different product).

Probably the easiest way would be to just send an email to your host and ask.