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

17-8 An Introduction to HP-GL/2 Vector Graphics EN
The next section explains how the syntax of individual commands is
presented.
Notations Used to Express Syntax
The following describes the notations used in the syntax section of
each command description:
Mnemonic
For readability, the mnemonic is shown in uppercase and separated
from the parameters and/or terminator.
parameters
Parameters are shown in italic.
[ ]
Parameters in square brackets are optional.
[param1,param2...[,param1,param2]]
These optional parameters must be paired.
params...params
These parameters may be given the number of times specified in the
command description.
text...text
This parameter indicates that you can type in a range of ASCII
characters, such as in the Label (LB) command.
(....)
Indicates that you can use a range of the previous parameter;
however, all X coordinates must have a corresponding Y coordinate.