I just stumbled upon this:
Antonia De Donatis (author of the Friends of Ed book: Advanced Components) whipped up this site last month. (Feb 2007)
XLEFF stands for: XMLÂ Layout Engine for Flash
Basically it is an xml document that describes the layout of your UI components for use in Flash MX2004 or in Flash 8.
It seems to be an alternative to using Flex. (Antonio seems to lean toward this way. He doesn’t say it explicitly on his site.) At least, you have to use AS2 and the Flash IDE (I suppose you can use an external editor as well with MTASC.)
I’ve used this method since working on Flash 6. (Well, in a very primitive way.) I always preferred using XML to place UI objects on the stage. It’s much better to modify text content in an xml file and let graphic artists concentrate on animating instead of opening up the Flash IDE, and making changes through there.
Antonio does mention though that as we are close to the next version of the Flash IDE (Flash 9), he still expects that it could be useful for the next couple of years. I tend to agree that the clients that I work with are very slow to upgrade, and many of them just upgraded on Flash 8, few to Flash 9. At my job, the company also tends to upgrade software once the first service pack comes out. (Can you believe that I work with Windows 2000?) There is always the issues of security and stability.