This operation returns a structure that describes the device. The first byte is set to an ioctype of DD_DLC. The subtype and data are defined by the individual DLC devices. See the /usr/include/sys/devinfo.h file for details.
The IOCINFO ioctl operation is selectable through the fp_ioctl kernel service or the ioctl subroutine. It can be called from the process environment only.
Generic Data Link Control (GDLC) Environment Overview in AIX 5L Version 5.2 Communications Programming Concepts.