I've never actually used PHP before, so obviously, take this with a (huge) 3 carrot grain of salt, but it looks like your trying to get PHP to work
within a string constant.
I'd have thought it would have been better to have PHP return the entire (computed) string instead. Just a thought.
Oh stupid me. You mean from the client, passing data back to your server using URL variables.
In other words, that fact that the server is using PHP isn't significant. I was looking at it from the Server side, and thinking you were using some kind of wierd PHP shortcut syntax that I'd never seen before... move along, nothing to see here...