ILE COBOL Programmer's Guide


Processing an Externally Described Transaction File

When an externally described TRANSACTION file is processed, the operating system transforms data from your ILE COBOL program to the format specified for the file and displays the data. When data passes to your ILE COBOL program, the data is transformed to the format used by your ILE COBOL program.

The operating system provides device control information for performing input/output operations for the device. When an input record is requested from the device by your ILE COBOL program, the operating system issues the request, and then removes device control information from the data before passing the data to the program. In addition, the operating system can pass indicators to your ILE COBOL program indicating which, if any, fields in the record have changed.

When your ILE COBOL program requests an output operation, it passes the output record to the operating system. The operating system provides the necessary device control information to display the record. It also adds any constant information specified for the record format when the record is displayed.

When a record passes to your ILE COBOL program, the fields are arranged in the order in which they are specified in the DDS. The order in which the fields are displayed is based on the display positions (line numbers and positions) assigned to the fields in the DDS. Therefore, the order in which the fields are specified in the DDS and the order in which they appear on the display need not be the same.


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