HP PCL/PJL reference - Printer Job Language Technical Reference Manual

EN PJL Status Codes D-19
Foreground Paper Loading (41xyy)
Foreground paper loading messages are sent when one of the paper
input sources is out of paper and there is no other input source
available and loaded with the correct paper size. When this occurs,
the printer goes offline until someone loads paper.
The messages are in the format 41xyy. The following tables list the X
and Y values for these messages. For example, 41303 is a
foreground paper loading message indicating to load the LC tray with
legal-size paper.
X = Tray Code Tray
0 Multi-Purpose Tray or
Envelope Tray
1 Manual Feed
2 PC Tray or Universal Tray2
3 LC Tray or Universal Tray3
4 EE Tray or Envelope Feeder
5 Any HCI Tray
9 All Trays Empty
YY = Media Code Media Size
00 Unknown Paper
01 Unknown Envelope
02 Letter Paper
03 Legal Paper
04 A4 Paper
05 Executive Paper
06 Ledger Paper
07 A3 Paper
08 COM10 Envelope
09 Monarch Envelope
10 C5 Envelope