MDAC 2.5 SDK - OLE DB Programmer's Reference
Chapter 26: Mapping MDX to SQL Statements

WHERE Clause

The tables corresponding to the axis specifications are joined with the FACT table. The WHERE clause on the MDX statement appears on the WHERE clause of this SELECT statement, whose select list contains the VALUE column and the RANK columns. Each row in the virtual table created by this SELECT statement represents a cell in the dataset. The RANK column contains the Cell ordinal. When taken together with the axis tables described in the section "Axis Expressions," this table represents the entire dataset.