You create the defined format for a major code by using TRCUST. The system formats trace entries to represent the actual major code by descriptive text instead of just numbers. In addition, the system can format data saved by the trace entries instead of being displaying the data as hexadecimal numbers. The use of TRCUST is completely optional.
The trace source file (.TSF) contains lines that describe the format of each major and minor code. TRCUST uses the .TSF file to generate .TFF files (trace format files). TRCUST generates one .TFF file for each major code. The trace formatter program uses the .TFF files to determine how to format the trace point entries being displayed.