LU 6.2 protocols control synchronous communication between peers. Both of the points communicating have similar communication processing capability. They might not have equal processing power, but they are capable of fulfilling the basic communication functions of a type 6.2 LU. A PC, for example, does not have the processing capabilities of a mainframe.

LU 6.2 peers are program processes running on one or more computers. For example, a personal computer can use software such as Communications Server for OS/2 to appear to programs in the host as another application program instead of a terminal. LU 6.2 can also be implemented in microcode (or even in hardware) on devices such as line printers or terminals. The LU 6.2 protocol is equally applicable to line printers and to complicated, distributed database operations.

Throughout this book, the term application program is used to describe the LU 6.2 peers that are communicating. These peers can be anything capable of implementing the LU 6.2 protocol, including microcode and hardware logic.