SWX is the native data format for Flash. Data is stored as SWF bytecode (you can't get more native than that on the Flash Platform) that is interpreted by the Flash Player. The SWX format is a subset of the SWF format (just like JSON is a subset of JavaScript).

With ActionScript 3 support, SWX provides you with custom events which are dispatched when your data is received, and it is available for use immediately. Using ActionScript 2, you can loadMovie() SWX data files and they are ready to use the moment they are loaded. When using either language you don't need to deserialize or massage the data in any way before using it as it is stored in native Flash objects.

For questions, please see the project wiki, submit an issue, or join the discussion and support list at http://groups.google.com/group/swx-format.