Sergio,
Appreciate your response. My mistake regarding SP level. I'm currently using SP10 not the non-existent "13" I mentioned in my post!
In the Graphical Calculation View, I've had success passing Input Parameters with multiple values. The issue I'm seeing is when a non-mandatory Input Parameter is left blank. The assumption is leaving a non-mandatory input value will not impact a filter expression, in other words, a "select all" would be the outcome for that specific param. This is not the case and thus the discussion topic. Is this the correct behavior? I'll try to add some documented screenshots but it doesn't appear I can attach anything but images...