This read-create OCTET STRING holds the Tuple's second value slot, flexible enough to carry an IPv4 address, an IPv6 address, a MAC address, or a protocol number combined with a mask. An admin uses this when the classification match needs a structured, potentially masked value, like matching a whole subnet or a MAC address range, rather than the plain-integer-only first value slot. For example, to build a rule matching an entire /24 IPv4 subnet, the admin encodes the network address together with its mask into this octet string field.