ifPortDisableLearningIndex is a read-only INTEGER that identifies an interface in the portDisableLearningTable, matching the ifIndex values used in the standard RFC1213 ifTable, and serves as the table's index. Admins use it to select which specific port's MAC address learning setting they are reading via the paired disableLearning object. An admin checking whether learning is disabled on port 8 would look up the row where ifPortDisableLearningIndex equals 8.