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.
