Attribute relationships are internal objects of the Analysis Services MultiDimensional Engine. They are not visible for the MDX client, can only be used indirectly and can only be configured in the development environment. However, they affect MDX objects and implicit behaviors. Understanding relationships is therefore essential for understanding MDX.

This article describes how the Analysis Services Multidimensional engine implicitly expands an incomplete tuple such as ([East]) to a complete tuple such as ([East], [2018], [Amount], etc.). This knowledge is crucial to understand how engine internals affect the way a cell value is computed.