Disposition Codes in IWS

[JeffreyT]

Hello everyones,
Was wondering if someone could help on that one.
I'm using IWS 8.1.200.27 (with no customization at this point) and I have configured it to display Disposition Codes based on a Business Attribute of type "Interaction Operational Attribute", which I've created as described in the deployment guide.
This Business Attribute holds two values "Case 1"(default) & "Case 2".

When I operate IWS I can see the 2 values, but the thing which puzzles me is that there is an extra 3rd value of "None" showing first.

Would anyone know where is this 3rd value coming from ? and if it can be removed (or hidden) by mean of configuration only (I'm trying to avoid the Visual Studio weapon at this time) ?
Thanks for reading this.