GTF traces the CCW pointed to by SCSW-8. GTF also traces the data that certain fields of the CCW pointed to by SCSW-8 reference. These fields are the data address and count fields. For further information on these fields and the data they reference, see the CCW section in Principles of Operation

Usually, when GTF issues this message, GTF cannot trace the entire channel program. GTF cannot tell if the traced CCW (the one pointed to by SCSW-8), is using the command code of a previous CCW. In other words, GTF cannot tell if the CCW is part of a data chain. Thus, the CCW command code might be incorrect. Because GTF cannot check the CCW command code, the I/O operation might not transfer data.