Is it ok to refer to a member of a const reference on the right side of the assignment?

[Patrick Horgan]

This gives a seg fault on the access to the model member of op, since at 
that point the &op is 0.

                    const
                    operand&    op = (*top->operands).select(0, op.model);


Should this work?  Can you refer on the right side of the assignment to 
the const reference?

Patrick