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

22-12 The Line and Fill Attributes Group EN
Figure 22-7 HP-Defined Shading Patterns
For fill type 11, the option1 parameter selects the corresponding
HP-GL/2 user-defined raster fill using the index number specified in
the RF command. Refer to the Raster Fill Definition (RF) command
for more information about creating user-defined fill types. If you have
not issued an RF command, the printer uses solid fill.
Figure 22-8 HP-GL/2 User-Defined Pattern