This read-create object defines the reference point, or start of offset, within a packet from which a custom byte-pattern match begins, as part of a user-defined classification rule. An admin building a classification rule for traffic that standard ACL fields cannot match, like a proprietary protocol header, uses this to anchor exactly where in the packet the custom match should start looking. For example, to classify traffic based on a vendor-specific byte a fixed distance into the Ethernet payload, the admin sets this offset type to anchor the match relative to the start of the packet or a known protocol boundary.