An apparatus, system, and method are disclosed for determining the location of intermediate CRC in a data stream sent from a channel subsystem to a control unit of an I/O processing system. A CRC locating module determines the location of at least one intermediate CRC in a transport data information unit. A CRC offset module determines a CRC offset of the at least one intermediate CRC. The CRC offset is a value identifying the difference between the location of the at least one intermediate CRC and the location of the first byte of user data in the transport data information unit. An offset block creation module creates a CRC offset block which includes a CRC offset value for each of the at least one intermediate CRC within the transport data information unit and a transmission module transmits the COB to a control unit in the I/O processing system.