Check Mate - check if reference set contains one solid body

Hello everybody

I`m trying to make some test using Check Mate, which will check, if the specified reference set contains only one solid body.

I think the most job of my requirement I can do using one of the template checks, called "Check Reference Set/Object Mappings". Using this check I can investigate if specified reference set has specified type of geometry. But, how can I check, if in this reference set is only one solid body, not more?

Thank you