This read-only integer, part of the EZ2Route control table, identifies the chassis slot associated with the EZ2Route control settings in this entry; the source description is empty, so this is inferred from the object's name and its sibling control objects for boosted-router and host timeouts and auto-learn mode. An admin uses this to know which specific slot's EZ2Route timeout and auto-learn settings a given table row governs, on a chassis with multiple routing modules. For example, an admin adjusting EZ2Route timeouts on one specific line card would locate the correct row using this slot value.