Parallell build

I wonder if it's at all possible to have mmk do parallell builds.  I understand that this would be tricky, considering the one-DCL-for-all model (as opposed one-shell-per-action-line that's the usual Unix model).  Still, I gotta wonder if it would be at all conceivable, with the understanding that description files will have to be written, or possibly treated a bit differently.
