Psuedo synchronous - asnychronous lingo
From Director Online Wiki
Imagine having a big project based on fileio that needs to be converted to use netlingo for saving data. Hmm.. big rewrite. But maybe not.
Imagine being able to call a handler that does some netlingo stuff and returns when the operation is complete (without using repeat loops of course!).
This is technically possible using the play/play done construct.
You can find a demonstration movie that illustrates the concept, plus a mini-tutorial full of caveats at [1] (http://nonlinear.openspark.com/tips/other/playDone/)