Confused by smart list operators

[jowidi]

I still can't grasp some of the fine points of smart list filtering. E.g. I wanted to create a filter that shows only songs where the 'Artist' field is empty. My first try was to use the filter " 'Artist' contains -nothing- " - but that list came up empty. Only when I used " 'Artist' equals -nothing- " I got the desired result. What exactly is the difference in this special case?

[arlo]

"Contains nothing" is a strange way to ask if someone is empty, and might be confusing the computer in the same way that "divided by 0" would. This is like asking someone if their pocket contains some emptiness. It would be more clear to ask them if their pocket is empty.

[jowidi]

There was emptiness in my brain but you helped me to grasp the Zen of querying, great master 

[arlo]

Ha ha, okay!