This week's book giveaway is in the Mac OS forum. We're giving away four copies of a choice of "Take Control of Upgrading to Yosemite" or "Take Control of Automating Your Mac" and have Joe Kissell on-line! See this thread for details.
In the EL, an unqualified name, such as cart in this example, is expected to be a scoped variable in one of page, request, session or application scopes. Because there is no qualification, the EL will search the scopes for "cart" in that order.