The FrontPage Substitution Component inserts text on the page that is the value of a variable in your FrontPage web. There are four built-in variables that you can insert:
Along with inserting built-in variables, you can use the FrontPage Substitution component to insert any variables you have added to a FrontPage web, using the Web Settings command in the Tools menu of the FrontPage Explorer. For example, you could add a variable to store your fax number and use a Substitution Component to insert it on pages in your FrontPage web. When you change the value of the variable (for example, your fax number) FrontPage will update the Substitution Component on all pages, updating your fax number.
Some FrontPage web wizards add variables to FrontPage webs that you can also insert on a page.