Brother HL-1050 Technical Reference Manual page 253

5. PostScript-Specific Variables
The following values are PostScript ( BR-Script ) specific and can be set and requested using PJL. The BR-
Script mode is standard in some models but may be available only when the optional BR-Script 2 ROM
board is installed into the printer. These variables must be set using the LPARM : IBM option.
CHAPTER 5 PJL - 46