This read-write OCTET STRING holds the actual pattern value to compare against the packet bytes selected by this OMPC's offset and mask, and must be the same length as the mask field. An admin sets this to the specific byte pattern that, combined with the mask and condition operator, defines what the rule is looking for. For example, an admin building a rule to detect a specific protocol marker would set this pattern to that marker's byte value, paired with a mask covering the relevant bits.