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Associating Files with Input/Output Devices
SPECIAL. Figure 126 on page 262 shows a file description specification for a
display (WORKSTN) file FILEX.
*.. 1 ...+... 2 ...+... 3 ...+... 4 ...+... 5 ...+... 6 ...+... 7 ...+... *
FFilename++IPEASFRlen+LKlen+AIDevice+.Keywords+++++++++++++++++++++++++++++
FFILEX CF E WORKSTN
Figure 126. Identifying a Display File in an RPG Program
Note that it is the file name, not the device name (specified in positions 36 through
42) which points to the OS/400 file description that contains the specifications for
the actual device.
The RPG device types correspond to the above file types as follows:
Table 16. Correlation of RPG Device Types with AS/400 File Types
RPG Device Type AS/400 File Type
DISK database, save, DDM files
PRINTER printer files
WORKSTN display, ICF files
SEQ tape, diskette, save, printer, database
SPECIAL N/A
Figure 127 illustrates the association of the RPG file name FILEX, as coded in
Figure 126, with a system file description for a display file.
RPG program
FILEX
Device type =
DISPLAY
File name = FILEX
Device = WORKSTN
Figure 127. Associating a file name with a display file description
At compilation time, certain RPG operations are valid only for a specific RPG
device name. In this respect, the RPG operation is device dependent. One example
of device dependency is that the EXFMT operation code is valid only for a
WORKSTN device.
Other operation codes are device independent, meaning that they can be used with
any device type. For example, WRITE is a device-independent operation.
The SEQ Device
The device SEQ is an independent device type. Figure 128 on page 263 illustrates
the association of the RPG file name FILEY with a system file description for a
sequential device. When the program is run, the actual I/O device is specified in the
description of FILEY. For example, the device might be PRINTER.
262 ILE RPG for AS/400 Programmer's Guide