cardDescription is a free-form text field, up to 64 characters, holding a description of the equipment unit in this slot. Admins can use it to record a human-readable label for the card, such as its role or location, making it easier to identify at a glance during inventory review or troubleshooting. As an illustrative example, an admin might see something like "OC-48 Tributary Unit, Slot 7" populated here, though the exact wording depends on the device's own labeling.