This read-create PmInterfaceType object specifies the kind of interface, e.g., port, or another supported interface category, that this PM instance is attached to and collecting statistics for, per its description. This field determines how cienaCesPmInstanceInterfaceId should be interpreted, since the same numeric interface ID means something different depending on whether the instance type is 'port' versus some other interface category. An engineer creating a PM instance would set this field to match the actual kind of resource being monitored, since setting it incorrectly would cause the accompanying interface ID to be misinterpreted.