WebIntelligence Filter for Null values or # on BW universe

XI 3.1 SP3 WebIntelligence on SAP BW UIniverse. When running a bex query we get values in the results set where a date field is # which I understand to be the default value from SAP when it is unassigned or NULL. Not sure of the sap terminology for this # or Hash.

Now, I am trying to replicate that bex query with a Web Intelligence Query built on a univrese that is derived from that Bex Query. If I run the query, it only returns values where the date is populated. if it is = # then no records return.

What I actually want is ONLY the records where the date field is unassigned or null. If in the query I build a condition that says where date = # it returns nothing. There is no operator for Is null or is not null since it is a BW universe. How do I return values where the date field is equal to "#" ?