The Cable Modem Interface Mask (CMIM) signaled in a Packet Classifier Encoding. In a Downstream Packet Classifier Encoding, a specified CMIM value restricts the classifier to match packets with a Destination MAC address corresponding to the interfaces indicated in the CMIM mask. The eCM self and any eSAFE interface bits correspond to the individual eCM and eSAFE host MAC addresses. In an Upstream Packet Classifier encoding, a specified CMIM value restricts the classifier to match packets with an ingress bridge port interface matching the bits in the CMIM value. If the CMIM subtype was omitted, this object should be reported as a zero length octet string.