SSI is short for Server Side Include, and is essentially a way of running CGI scripts within HTML pages. They are like RXML tags, but not as flexible. SSI is a standard that works on several web servers.

SSI support is handled through the Main RXML parser and is turned off by default.

SSI works like a simple pre-processor for HTML, and reads directives that are hidden in HTML comments. One directive, <!--#exec-->, allows a user to execute programs and is thus a potential security hazard. The programs will be executed as a user with few privileges, by default nobody. The directive can also be disabled altogether.