For those interested in how to package up your Flash files for distribution via MXPs. I’ve just finished a general article on how a .MXI (mixy) is structured, including an example file to play with. If writing .MXI files for use in .MXP’s isn’t your bag there are a few links on .MXI makers at the bottom of the piece.
It is Flash-centric taken from the point of view that you’re looking for a cleaner way to package and distribute your work for consumption by other developers working with the same tools or for submission to the Adobe Exchange.
You can read more here