HP PCL/PJL reference (PCL 5 Color) - Technical Reference Manual

7-18 Color Vector Graphics (HP-GL/2) EN
If the currently selected pen is outside the range of the new palette
size, the SP command modulo function is applied to obtain a pen
number which will index into the new palette; this clears the current
residue (the unused portion of a pattern) and terminates any
sequence of continuous vectors. For more information, see the
descriptions of the Line Attribute (LA) and Line Type (LT) commands
in the PCL 5 Printer Language Technical Reference Manual.
The number of pens is defaulted by an IN command.
This command is ignored if the current palette was created by the
Simple Color command (
?*r#U) or ?E.