HP LaserJet 4000 Printer series - Manual (Page 167)

D-2 Printer Commands
EN
Understanding PCL Printer Command
Syntax
Before using printer commands, compare these characters:
Many printer commands use the lowercase letter l (l) and the
number one (1) , or the uppercase letter O (O) and the number zero
(0) . These characters may not appear on your screen as shown
here. You must use the exact character and case specified for PCL
printer commands.
Figure D-1 displays the elements of a typical printer command (in
this instance, a command for page orientation).
Figure D-1 Printer Command Elements
Lowercase l: l Uppercase O: O
Number one: 1 Number 0: 0
Escape character
(begins escape sequence)
Value field (contains both
alpha and numeric characters)
Category of command
Uppercase letter
(terminates escape sequence)