QTR-Quadtone RIP

Hi ...

I've read nearly every document about creating curve in QTR. I've learnt how to specify ink limit for darkest black ink and the relative densities of other inks.

But, I could not find any document explaining how to decide the ink limits for lighter blacks and toner inks. User guide of QTR just says that ink limits are judgment calls.

Is there any exact method for specifying ink limits for lighter blacks and toner inks? Any document?

Or, it is just an trial-and-error process?

Thanks.