An HTML command used to place up-to-date data as well as common data (boilerplate) into a Web page before sending it to the user. For example, it can be used to retrieve the current date and size of downloadable files that are constantly changing. It can be used to insert a boilerplate message where only the boilerplate needs to be changed to bring all the pages up-to-date. HTML pages that contain server-side includes often use the .shtml file extension.The Include command inserts the contents of another document at the tag location. Echo inserts the contents of an environment variable. Fsize and Flastmod insert size and date of a file, and Config controls the format of the output. The Exec command executes a program, script or shell command. See SHTML.