When you enter one of the previous commands in the prefix area of a line, the command performs its respective function on that line. If you enter an "I" in the prefix area of line 00000, the editor opens a new line just below it for input. You can also append a number to the end of the prefix command. This acts as a replication factor. If the number "5" is appended to the "I", five lines are opened for input instead of one.