True or False: When inserting a Program Instruction, you must highlight either a line number or END.

Highlighting either a line number or the END statement is essential when inserting a Program Instruction in FANUC programming. This requirement ensures that the control system recognizes the exact location for the new instruction to be added within the program, thereby maintaining the program's structure and execution order.

By highlighting a line number, you inform the system precisely where to insert the new instruction, ensuring that it integrates seamlessly into the existing program sequence. Highlighting the END statement serves a similar purpose, indicating that you wish to place the new instruction just before the program concludes, which is critical for proper execution.

This practice is foundational in programming with FANUC systems, where maintaining correct program flow and sequence is vital for achieving the intended operational results. Therefore, the statement is true, as highlighting provides the necessary context for program modification.