MDAC 2.5 SDK - OLE DB Programmer's Reference
Chapter 24: Multidimensional Expressions
In the expression template shown in "Parts of an MDX Statement," the FROM <cube_specification> clause specifies the cubes to query. The cube specification is just the name of the cube. If multiple cubes are involved, it is the comma-separated list of those cube names.
Note The ability to query across more than one cube is not part of core level MDX language. In other words, a provider need not support cross-cube queries in order to be compliant with OLE DB for OLAP. Applications can check the property MDPROP_JOINCUBES in the DBPROPSET_DATASOURCEINFO property group to determine whether a provider supports this functionality.
For SalesCube, the FROM clause looks like this:
FROM SalesCube