This is the maximum chassis ID accepted by this pool qualifier, per its ChassisQual maxId property, bounding the upper end of the chassis-ID range that qualifies for the pool. This value is exactly what an admin checks when a chassis isn't being picked up into an expected server pool — if the chassis's numeric ID exceeds maxId, that specific chassis is excluded by policy even though it otherwise matches. A maxId of 4 on a qualifier means chassis IDs 5, 6, 7 and higher in the domain are silently excluded from that pool no matter what else matches.