This read-only field identifies the source of a current chassis alarm using one of three specific string formats: the literal word 'Chassis' for chassis-wide alarms, 'Submodule' for a card-level alarm, or a structured 'port@slot#/subslot#/port#' string for an alarm traced to a specific physical port -- and the description explicitly warns that management software must recognize all three formats since no other value is considered valid. An admin or NMS parsing this field needs conditional logic to handle each format differently, since a chassis-wide alarm requires very different troubleshooting than one pinpointed to a specific port. For example, a value of 'port@3/1/2' tells the admin the alarm is localized to port 2 on sub-slot 1 of slot 3, letting them go straight to that connection rather than inspecting the whole chassis.