[Chameleon] Ruler's UNITS attribute - required?

[McGraw, Joanne]

Last question...

The Ruler widget's UNITS attribute is currently a required attribute.
Does it have to be? I changed it to be optional and it appeared to work
fine. It simply used my map's UNITS to report the distances, which is
exactly what I expected it to do. 

So, my question is: does anyone know of any problems I may be
introducing by changing the Ruler widget's UNITS attribute to be an
optional one?

Cheers,
jtm