Report Filters for null and not null queries

Summary:

I need to be able to create a filter that if blank will return rows with that column blank, but if not blank then return rows that match the filter

Content (required):

In this instance I have to records one with a 'No value' and one with 'RECORDED', I need to be able to have a filter than can return only 'no value' or 'recorded'

To return the 'Recorded' row i use the following:

which returnss only the 1 row, as expected

But what do I need to do in the filter to be able to only return the 1 row for the 'No value', is there some special text\characters that I can enter in the SymMaintenanceStage to return the 'No Value' row