The set command is used to create your own variables within an Active Page. The resutls of set last for the lifetime of the request, and do not affect any other subsequent or concurrent requests.
You can use the set command to over-ride the SPML values of Forms data, and the Request Headers. For example,if there is a forms field named "TEST_VAR" and you redefine TEST_VAR using the SPML set command, subsequent SPML will recognize the value defined by the set command.
HTML and other data may be stored in a user variable for use in other SPML commands (echo, if, and others) that accept user variables. This sample creates a variable named "NEW_LINE" and sets it to the HTML break tag, followd by a Return.
<!-- #set var="NEW_LINE" value="<br>