The Excel function: CUBEMEMBER

Returns a member or tuple in a cube hierarchy. Use to validate that the member or tuple exists in the cube.

More information:

Other functions
Returns a key performance indicator (KPI) name, property, and measure, and displays the name and property in the cell A KPI is a quantifiable measurement, such as monthly gross profit or quarterly employee turnover, used to monitor an organization's performance
Returns the value of a member property in the cube Use to validate that a member name exists within the cube and to return the specified property for this member
Returns the nth, or ranked, member in a set Use to return one or more elements in a set, such as the top sales performer or top 10 students
Defines a calculated set of members or tuples by sending a set expression to the cube on the server, which creates the set, and then returns that set to Microsoft Office Excel
Returns the number of items in a set
Returns an aggregated value from a cube