How To Create a Custom Query in a CQWP

Question

I am in the Content Query Tool Part, filtering my list with Managed Metadata Tags. My choices are "contains any of" and "contains all of". What I want is "does not contain", which is not listed. I am expecting the next input box in the CQTP, Custom Value or Query, will allow me to write a custom query against my MMT column for "does not contain". Does anyone have example syntax of what this query should look like for this input box?