This optional attribute specifies the value of the id attribute for another Sous-processus Arbortext PE pool that can take overflow of processing requests. The cascade attribute allows one pool to take the overflow from another to improve servicing requests. If the Sous-processus Arbortext PE pool being queried determines that it can accept an HTTP request, but no Sous-processus Arbortext PE are available and no additional Sous-processus Arbortext PE can be started, the pool will pass the request to the pool identified by its cascade attribute. You can configure a series of pools to cascade from one to another, where pool A can cascade to pool B, pool B can cascade to pool C, and so on.