A line number is automatically inserted next to each instruction you add to a program. If you remove an instruction or move an instruction to a new position in the program, the program instructions will be renumbered automatically so that the first line is always line 1, the second line 2, and so forth. You use line numbers to identify which lines to move, remove, and mark when you modify a program.
The program end marker ( [End] ) automatically appears after the last instruction in a program. As new instructions are added, the program end marker moves down on the screen, retaining its position as the last line in the program.