[eclipse-users] Undefined value

Hello,

I am working in a model where there is a special value, ND (Not 
Determined) which
should be considered for every single operation.
I use finite domain constraints but it would be great if it was possible 
to redefine every operation
to allow propagations like:

Given:

[X,Y,Z]::[0..100,ND],
X + Y #= Z

Thus, if X or Y is ND, then Z is ND

The point is that several operations should be redefined. What is the 
best way to do this?

Thank you in advance,
Daniel