If an attribute has a large number of members, you can choose to group those members into buckets, reducing the number of members that users see when they browse the data in a hierarchy. You can also determine the number of buckets in which the members are groups and set a naming scheme for the buckets. For more information, see Group Attribute Members (Discretization).
You group members by setting the DiscretizationMethod property, which is accessed through the Properties window in SQL Server Data Tools (SSDT).
When you create member groups, your changes are not available to users until you process the dimension. For more information, see Processing a multidimensional model (Analysis Services).
To create member groups
Open the dimension that you want to work with. The Dimension Structure tab opens by default.
In Attributes, right-click the attribute whose members you want to group, and then click Properties.
From the drop-down list next to DiscretizationMethod, select a method by which to group the members. For more information about DiscretizationMethod settings, see Group Attribute Members (Discretization).