How to concatenate or add to crossed coverpoints

In reply to dave_59:

Hi Dave,

Summing a cross as in adding the occurrences of a,b and c.
if a,b and c have 36 combinations each. I want to be able to quantify a coverpoint that counts 108 combinations (a+b+c)

I believe if i cross a,b and c i will end up getting 36^3 combination buckets.