Thank you for your promt answer, I guess I should have been more explicit, sorry.
I am scripting a Bivariate Analysis for a large numner of chips and reticles and so need to set it to zero in the code:
E.g.,
BivAnalysis = Bivariate(
Y ( Eval(yparam)),
X( Eval(xparam)),
Fitline ( {Line Color()}),
);
Thanks for all the help!