The <a href="http://www-sop.inria.fr/meije/personnel/Gerard.Boudol/blue.html">Blue Calculus</a> is a _(Pi Calculus) variant by <a href= "http://www-sop.inria.fr/mimosa/personnel/Gerard.Boudol.html">Grard Boudol</a>. Its primary motivating difference is to handle asynchronous operations more cleanly.

It is, of course, an *(abstract VM).
