Currently, ReportBuilder lets you specify a range of cells you would like to filter values of a report by.
But sometimes I have a list of values I want, but I need a report to show me all values that are outside that list. This works as a catch-all request for values that you don't expect to show up in report. It is mainly for debugging, but good use case scenarios are to generate a list of erroneous tracking codes, or a list of Recommending Pages that for ome reason show that people have clicked on recommendations even though they have no recommendations.
The current functionality to select a range is the one below, but I think adding an exclude option will make life easier.