Old 43BSD and netstat output

On old 43BSD... netstat -f unix Active UNIX domain sockets Address Type Recv-Q Send-Q Inode Conn Refs Nextref Addr 801ca38c dgram 0 0 8008b5c0 0 0 0 /dev/log 801cc10c stream 0 0 8008e690 0 0 0 /dev/printer Address #socket address type #type: stream or dgram Inode #Inode? Conn #sockets connections Refs #? Nextref #? Addr #socket file Anyone know what does it mean "Refs" and "Nextref". As I know Refs is referred to routing, but in sockets there is no routing as I know.