xapi:delivery - Explains where the output should be delivered
xapi:filesystem - explains the output is destined to filesystem
xapi:template - specifies the template shortcode prefixed with app short code, for eg: AR.INVOICE - AR-app short code and INVOICE is the xml template short code.
Above line is very important, it takes care of pulling the latest template uploaded in the XML Publisher Administrator responsibility, you don't need to put your template hanging in any UNIX servers.
en - Language
US - Territory code (when you create template definition, you make sure that you select United States or other country)
The same above example holds good for sending the output through email, fax, etc.,