Slicer dimensions filter cube data and can be used to limit the data returned in the dataset.
Dimensions not explicitly assigned to an axis are assumed to be slicer dimensions and filter with their default members. The default member of a dimension is the All member if an “(All)” level exists, or else an arbitrary member of the first level. (The name of the All member is not necessarily “All”.)
Slicer dimensions can also be specified explicitly by using the WHERE <slicer_specification> component of the syntax shown in Parts of an MDX Query.
The slicer dimensions for the example dataset shown in Cube and Dataset Example are Measures, Years, and Products. These slicer dimensions limit the dataset to Sales (in the Measures dimension), 1997 (in the Years dimension), and All (all products in the Products dimension). For the example dataset, the <slicer_specification> value is:
WHERE (Sales, [1997], Products.All)
Because the member name “All” might not be unique within the cube, it is recommended to qualify it with the dimension name to make it unambiguous.