The server I am on requires server side includes to have a shtml extension, and php scripts to have a php extension.
How do I get both to work on the same page?
You cant use SSI inside a PHP document and you cant use PHP inside an SSI document. You could tell apache to parse .shtml files as PHP using .htaccess but that would disable any SSI tags as, like I just said, you cant use SSI inside PHP.
why use ssi when you can include files in php scripts using the include function?
http://www.php.net/include