If cubes contain parametric dimensions, one can set up control over parameters of these dimensions via other cube dimensions. In this case values of specific attributes should be passed as parameter values. All parametric dimensions are displayed on the Controlling Dimensions page:
The Parameters box shows parameters of dimensions and the query, controlling dimensions of which can be defined.
Clicking the Edit button opens the Control Parameter Properties dialog box:
The dialog box is used to set the following parameters:
Controlling Dimension. In the drop-down list select the dictionary that will be a controlling dimension.
Controlling Expression. An expression for the controlled parameter is set in the Expression Editor dialog box, which opens on clicking the 
Set Formula button. Data area of the formula editor displays each attribute of the controlling dictionary with the functions:
First. Value of the first element attribute in the existing controlling dimension selection is passed to the parameter.
Last. Value of the last element attribute in the existing controlling dimension selection is passed to the parameter.
All. The function passes the array of attribute values of all elements included in the controlling dimension selection. This function should not be used as it is. It is required to pass the array of values to a custom function, which calculates the value and passes it to the parameter of the controlling dimension.
A controlling dimension and controlling expression will not be determined for the controlled parameter on clicking the Clear button.
See also:
Multidimensional Calculation on Database Server