Start = 241 + Offset
Character_Length = Length (in bytes)
Offset = 30
Data Type is character
Length = 2
Start = 241 + 30 = 271
See subfield DEV_CLASS in the example below
DCL-F MYFILE WORKSTN INFDS(MYIOFBK);
DCL-DS MYIOFBK;
// 241-242 not used
WRITE_CNT INT(10) POS(243); // Write count
READ_CNT INT(10) POS(247); // Read count
WRTRD_CNT INT(10) POS(251); // Write/read count
OTHER_CNT INT(10) POS(255); // Other I/O count
OPERATION CHAR(1) POS(260); // Current operation
IO_RCD_FMT CHAR(10) POS(261); // Rcd format name
DEV_CLASS CHAR(2) POS(271); // Device class
IO_PGM_DEV CHAR(10) POS(273); // Pgm device name
IO_RCD_LEN INT(10) POS(283); // Rcd len of I/O
END-DS;