ROPE Language Reference - "$ip_frag_off"

The "$ip_frag_off" register contains the fragment offset of the packet being inspected. RFC_791 explains the meaning of this value like this..

Fragment Offset:  13 bits

 This field indicates where in the datagram this fragment belongs.
 The fragment offset is measured in units of 8 octets (64 bits).  The
 first fragment has offset zero.

See Also

RFC_791, $ip_check, $ip_daddr, $ip_dont_frag, $ip_id, $ip_ihl, $ip_protocol, $ip_saddr, $ip_tos, $ip_tot_len, $ip_ttl, $ip_version