(SPML, SHTML) A kind of HTML file containing server-specific, non-standard commands which are interpreted by the HTTP server and replaced by standard HTML or text before the data is returned to the client.
Different servers use different command syntax and support different sets of commands. The most common example is a server-side include command which simply expands to the contents of some given file and allows bits of HTML or text to be shared between pages for ease of updating. Other commands insert the value of an environment variable or the output of a shell command. These allow pages to be different each time they are served without requiring a CGI script.