Which programming language is NOT one of the four languages used for programming a CompactLogix PLC?

The programming language not used for programming a CompactLogix PLC is the Graphic User Interface. In the context of PLC programming, languages such as Sequential Function Chart, Structured Text, and Function Block Diagram are standardized within the IEC 61131-3 framework and are specifically designed for control logic applications.

The Graphic User Interface, on the other hand, is primarily focused on providing visual interaction for users rather than serving as a programming language for control logic within the PLC environment. It is used for the development of user-facing applications or control systems that enhance user interaction but does not function as a language for writing control instructions that govern the operation of the PLC. This distinction between programming languages designed for systematic control processes and tools designed for user experience is crucial in understanding the appropriate applications of each.