What is the php dummy file in nginx vhost config

I encountered the following in the site vhosts during some server customizations:

Code:

        location ~ \.php$ {
            try_files /b0cf9d78466b40a38f3a92c386818d84.htm @php;
        }

(source: http://git.ispconfig.org/florian030/ispconfig3/blob/master/server/conf/nginx_vhost.conf.master#L136)

I know it redirects to the actual php handling directive but I have no idea why there must be a randomly generated dummy file for every site.

Could anyone shed some light on this?

 

Because try_files requires at least two arguments, and because requests should be passed to @php, the first argument must be a non-existing file.

 

I'm guessing there's some advantage to this that I'm not seeing.

So, why not have the rules from location @php directive inside location ~ \.php$ and skip try_files altogether?