Specifies columns whose values are used as limits for
    partitioning the index across multiple storage areas. You cannot
    name columns not specified as index key segments.

    If the index key is multisegmented, you can include some or all
    of the columns that are joined to form the index key. You must
    specify the columns in the order in which they were specified
    when the index key was defined. If you include only a subset of
    the columns from the multisegmented index, you must include the
    leading columns of the index key.