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

1-6 Introduction to HP PCL EN
Parameterized Escape Sequences
Parameterized escape sequences have the following form:
? X y z1 # z2 # z3 ... # Zn[data]
where y, #, zi (z1, z2, z3...) and [data] may be optional, depending on
the command.
X Parameterized Character - A character from the
ASCII table within the range 33-47 decimal
(“!” through “/”) indicating that the escape sequence is
parameterized.
y Group Character - A character from the ASCII table
within the range 96-126 decimal (“ ‘ ” through “ ~ ”) that
specifies the group type of control being performed.
# Value Field - A group of characters specifying a
numeric value. The numeric value is represented as an
ASCII string of characters within the range 48-57
decimal (“0” through “9”) that may be preceded by a “+”
or “—” sign and may contain a fractional portion
indicated by the digits after a decimal point (“ . ”).
Numeric value fields are within the range -32767 to
65535. If an escape sequence requires a value field
and a value is not specified, a value of zero is
assumed.
zi Parameter Character - Any character from the ASCII
table within the range 96-126 decimal (“ ‘ ” through
“ ~ ”). This character specifies the parameter to which
the previous value field applies. This character is used
when combining escape sequences.
Zn Termination Character - Any character from the
ASCII table within the range 64-94 decimal
(“ @ ” through “ ^ ”). This character specifies the
parameter to which the previous value field applies.
This character terminates the escape sequence.
[data] Binary Data is eight-bit data (for example, graphics
data, downloaded fonts, etc.). The number of bytes of
binary data is specified by the value field of the escape
sequence. Binary data immediately follows the
terminating character of the escape sequence.