UNDEFVALS function

[appleglaze28]

I'd like to ask...how come when you apply UNDEFVALS in the rules..so empty cells appear empty & zero cells appear with zero. Testing the cube out...I put zero on a previously empty cell, so during zero suppression the data point with a zero isn't suppress...but when I clear the field cause I don't want any value, I can't make it appear empty. I assume when you use the data spread clear, you clear that cell as if there's no value.