This integer uniquely identifies a trapLogEntry at the moment it's read, with the most recent trap always at index 1 and the oldest at the value of cpqHeTrapLogMaxSize, shifting as new traps arrive. An administrator needs to understand this queue-like renumbering behavior so they don't mistake a changing index for a different event when polling the same underlying trap repeatedly. For example, a trap seen at index 1 during one poll might show up at index 2 on the next poll simply because a newer trap was logged in between.