DITTO command ---- Back Space Records
Backspaces a specified number of physical records on the specified DITTO device. The user has the option to backspace records on the input device or output device.
- DEVTYPE
- Device type. Specifies which input/output device is to be processed. Valid values are:
= INPUT: Input device = OUTPUT: Output device
- NRECS(0)
- Number of records. Specifies the number of physical records to be backspaced on the input or output device.
The user has specified to backspace two physical records from the current position on the input device.
Before: file ptr. | v ------------------------------------------------ | | | | | |E| |record 1|record 2|record 3|record 4|record 5|O| | | | | | |F| ------------------------------------------------ After: file ptr. | v ------------------------------------------------- | | | | | |E| |record 1|record 2|record 3|record 4|record 5 |O| | | | | | |F| -------------------------------------------------
The user has specified to backspace four physical records from the current position on the output device.
Before: file ptr. | v ------------------------------------------------- | | | | | |E| |record 1|record 2|record 3|record 4|record 5 |O| | | | | | |F| ------------------------------------------------- After: file ptr. | v ------------------------------------------------- | | | | | |E| |record 1|record 2|record 3|record 4|record 5 |O| | | | | | |F| -------------------------------------------------
The parameters are input into the program. From the parameter DEVTYPE, it is determined which device is to be processed. The specified number of physical records are backspaced from the current position of the DITTO device.