Common I/O feedback area

See a detailed table listing the information that might exist in the common I/O feedback area.

Table 1. Common I/O feedback area
Offset	Data type	Length	Contents
0	Binary	2	Offset to file-dependent feedback area.
2	Binary	4	Write operation count. Updated only when a write operation completes successfully. For blocked record I/O operations, this count is the number of blocks, not the number of records.
6	Binary	4	Read operation count. Updated only when a read operation completes successfully. For blocked record I/O operations, this count is the number of blocks, not the number of records.
10	Binary	4	Write-read operation count. Updated only when a write-read operation completes successfully.
14	Binary	4	Other operation count. Number of successful operations other than write, read, or write-read. Updated only when the operation completes successfully. This count includes update, delete, force-end-of-data, force-end-of-volume, change-end-of-data, release record lock, and acquire/release device operations.
18	Character	1	Reserved.
19	Character	1	Current operation. hex 01 Read or read block or read from invited devices hex 02 Read direct hex 03 Read by key hex 05 Write or write block hex 06 Write-read hex 07 Update hex 08 Delete hex 09 Force-end-of-data hex 0A Force-end-of-volume hex 0D Release record lock hex 0E Change end-of-data hex 0F Put delete hex 11 Release device hex 12 Acquire device
20	Character	10	Not applicable to tape and diskette.
30	Character	2	Device class:
			Byte 1:
			hex 00	Database
			hex 01	Display
			hex 02	Printer
			hex 04	Diskette
			hex 05	Tape
			hex 09	Save
			hex 0B	ICF
			Byte 2 (if byte 1 contains hex 00):
			hex 00	Nonkeyed file
			hex 01	Keyed file
			Byte 2 (if byte 1 does not contain hex 00 and contains either hex 04 or hex 05):
			hex 08	Spooled
			hex 1A	9347 Tape Unit
			hex 1B	9348 Tape Unit
			hex 1C	9331-1 Diskette Unit
			hex 1D	9331-2 Diskette Unit
			hex 2A	6346 Tape Unit
			hex 2B	2440 Tape Unit
			hex 2C	9346 Tape Unit
			hex 2D	6331 Diskette Unit
			hex 2E	6332 Diskette Unit
			hex 3A	3430 Tape Unit
			hex 3B	3422 Tape Unit
			hex 3C	3480 Tape Unit
			hex 3D	3490 Tape Unit
			hex 49	6367 Tape Unit
			hex 4A	6347 Tape Unit
			hex 4E	6341 Tape Unit
			hex 4F	6342 Tape Unit
			hex 50	6133 Diskette Unit
			hex 53	6366 Tape Unit
			hex 54	7208 Tape Unit
			hex 5A	6343 Tape Unit
			hex 5B	6348 Tape Unit
			hex 5C	6368 Tape Unit
			hex 64	6344 Tape Unit
			hex 65	6349 Tape Unit
			hex 66	6369 Tape Unit
			hex 67	6380 Tape Unit
			hex 68	6378 Tape Unit
			hex 69	6390 Tape Unit
			hex 70	6379 Tape Unit
			hex 71	9331-11 Diskette Unit
			hex 72	9331-12 Diskette Unit
			hex 73	3570 Tape Unit
			hex 74	3590 Tape Unit
			hex 75	6335 Tape Unit
			hex 76	1/4-inch Cartridge Tape¹
			hex 77	1/2-inch Cartridge Taped¹
			hex 78	1/2-inch Reel Tape¹
			hex 79	8mm Cartridge Tape¹
32	Character	10		Device name. The name of the device for which the operation just completed. Supplied only for display, printer, tape, diskette, and ICF files. For printer or diskette files being spooled, the value is *N. For ICF files, the value is the program device name. For other files, the value is the device description name.
42	Binary	4		Length of the record processed by the last I/O operation (supplied only for an ICF, display, tape, or database file). On ICF write operations, this is the record length of the data. On ICF read operations, it is the record length of the record associated with the last read operation.
46	Character	80		Reserved.
126	Binary	2		Number of records retrieved on a read request for blocked records or sent on a write or force-end-of-data or force-end-of-volume request for blocked records. Supplied only for database, diskette, and tape files.
128	Binary	2		Record length. For output, the field value is the record format length, including first-character forms control, option indicators, source sequence numbers, and program-to-system data. If the value is zero, use the field at offset 42. For input, the field value is the record format length, including response indicators and source sequence numbers. If the value is zero, use the field at offset 42.
130	Character	2		Reserved.
132	Binary	4		Current block count. The number of blocks of the tape data file already written or read. For tape files only.
136	Character	8		Reserved.
Note: If the device is not listed in this table, use one of the following general categories: hex 76—1/4" Cartridge Tape hex 77—1/2" Cartridge Tape hex 78—1/2" Reel Tape hex 79—8mm Cartridge Tape