Hi Clarke,
Funnelback supports quite a few query operators which allows you to do things like scope and negate certain queries:
https://docs.funnelback.com/15.22/develop/reference-documents/query-language-help.html
Below are a few examples which might prove useful:
Querying for documents with an empty value for particular metadata:
<query> |-<metadata class>:$++
e.g. Query for all documents which does not have a value for metadata class author
!padrneull |-author:$++
Querying for documents that does not have a certain metadata value:
<query> |-<metadata class>:$++<value to exclude>$++
e.g. Query for all documents which do not have the value "Data Model" in the kbFeatures metadata class
!padrenull |-kbFeatures:$++Data Model$++
Hope this help.
~Gioan