I reread page 59 of the manual and this may be the explanation:

"Because it’s separate from the MASON core proper (and a bit new), I
don’t describe this package in detail,
but it should be fairly straightforward. Warning: the port of these
classes from COLT to MASON is new and
has not been tested much."

On Wed, Jan 30, 2013 at 2:56 PM, Tony Bigbee <[log in to unmask]> wrote:
> Hi - I see the sim.util.distribution*.java files in the mason.zip
> distribution, but the class files are not in mason.16.jar.  Is there a
> deliberate reason for this?  I notice that the distribution package is
> not in the DIRS variable for Makefile as of r862.
>
> Thanks.
> Tony