This attribute indicates if an UltraRAM is part of a cascade and the location of the UltraRAM in the cascade chain. The values are NONE (default), FIRST, MIDDLE, and LAST. All UltraRAMs that are first in each column should be set to FIRST and all UltraRAMs that are last in each column should be set to LAST. All UltraRAMs in between must be set to MIDDLE. See Cascade User Attributes for more information.