.rev file association issues

[Gary Rathbone]

This in an annoying distraction which I'm sure will have an easy answer.

When I save a rev stack I use (the suggested) .rev extension.

However I also use WinRAR which according to filext.com uses the .rev
extension (with a few other packages) as its own. This means WinRAR 'own' my
Rev stacks, when I double click it tries to open WinRAR.

Using XP I can usually change this file association. However a right click
on the stack and a click on the "Change..." button doesn't allow me to
select "revolution"; its not listed.

My first question is "How to I associate .rev to revolution?"

As there is only a fixed number of three letter file extensions. How does a
developer, considering cross platform data files for their owns stacks,
provide or register/'own' a unique or non conflicting filetype. 

Thanks in advance,

Gary Rathbone