This read-create AddressFamilyNumbers value indicates, per its source description, the network address type of the paired ptopoConnAgentNetAddr object, and should be ignored by an NMS if that address object is a zero-length string; it cannot be modified once the row is active. Admins use this to correctly interpret the network address type used to reach the remote SNMP agent managing the neighboring chassis/port, when such an address is known. For example, this reporting an IPv4 address family type tells a management tool to parse the paired address as a standard dotted-decimal IP address for reaching that remote agent.