Except statement Cognos Report Studio

[Revelator80]

I have created a set of unmapped suppliers by identifiying the ID for them. I now want to create an additional set for all the other suppliers to group these into a Mapped set. I think it's going to need the except function but I don't really know how to utilise it - my first attempt just brought back all the individual names again.

the set expression for the unmapped suppliers is:
member([CPD_Cube].[All Suppliers].[All Suppliers].[Supplier Name] ->

• , 'Unmap','Unmapped Suppliers',[CPD_Cube].[All Suppliers].[All Suppliers])
  
  Any help greatly appreciated.