This read-write integer stub exists to let the INS (an internal Cisco network/service management component) tag a resource with a customer identifier, based purely on its bare description referencing INS. An administrator or the INS management system would set it to associate a port, channel, or connection with a specific customer for billing or provisioning tracking. Because the source description gives no further detail, its exact numbering scheme is defined by the INS application rather than documented in this MIB object itself.