Create yourself a pivot table with any 3 dimensions. now set 2 expressions =Dimensionality() and =SecondaryDimensionality(). Ensure Partial Sums are ticked for all dimensions. Now drag one of the dimensions up to the top so it becomes horizontal. Take a look at the numbers...
Dimensionality() is mainly useful in pivot tables as it shows what level you are at. This enables some conditional expression or formatting to be used, for example in the background colour setting of an expression you could enter:
=IF(Dimensionality()=0,LightRed(),White())
Wherever Dimensionality was 0 (top level total) the background would be red, everywhere else it would be white.
You could also use it to show values in percent at a line level but real values in the subtotals, if you wanted to. The rweal power comes in showing different expressions when users expand dimensions as each expanded dimension adds another level of Dimensionality. SecondaryDimensionality is the same but for dimensions across the top.
