HP PCL/PJL reference (PCL 5 Printer Language) - Technical Reference Manual Part II

EN HP-GL/2 Commands and Syntax 17-9
Note Remember that while X,Y coordinates are shown in parentheses in
text [for example (3,4) or (0,0)], the parentheses are not part of the
syntax. Do not enter these parentheses in your commands.
;
iCommand terminator. In most HP-GL/2 commands, a semicolon is
optional, and is shown in parentheses in most command syntax.
Notes Three exceptions to the optional use of the semicolon as a command
terminator occur in the following commands: Polyline Encoded (PE),
Label (LB), and Comment (CO).
PE must be terminated by a semicolon. LB is terminated by the non-
printing end-of-text character (ETX - decimal 3), or a user-defined
character. The comment string of the CO command must be delimited
by double quotes.
A semicolon terminator is always required following the last
command prior to leaving HP-GL/2 mode.
,
A comma is always shown as the separator between parameters. A
space, +, or - is also valid (although not preferred). (A + or - is a valid
separator only for numeric parameters.)
Omitting Optional Parameters
Some commands have optional parameters that take on default
values if they are omitted. When you omit a parameter, you must omit
all subsequent parameters in the same command (the Define Label
Terminator (DT) command is an exception).
For example, the Line Type (LT) command has three optional
parameters: type, pattern length, and mode. The following command
shows all three being used (type = 6, pattern length = 25, mode = 1).
LT6,25,1