HP Color LaserJet 5500 Technical Reference Manual page 125

Comments:
When the printer receives the INFO command, it returns
the requested information. Only one category can be used
for each INFO command. Each category is described below,
with the format of the printer's response. If the printer does
not support the specified category, the returned information
is as follows:
@PJL INFO category <CR><LF>
"?" <CR><LF>
<FF>
ID Category
The INFO ID command provides a way to identify the type
of printer used. For the HP LaserJet 4 printer, the INFO ID
command prompts the printer to return the following
response:
@PJL INFO ID<CR><LF>
"LASERJET 4"<CR><LF>
<FF>
Note
To maintain compatibility with future printers, applications
should not use the INFO ID command to identify printer
features. Instead, the more detailed INFO CONFIG
command should be used (see the following discussion on
"The CONFIG Category").
Some printers, such as the HP LaserJet 4ML printer,
return "HP" in front of the model name, for example:
@PJL INFO ID<CR><LF>
"HP LASERJET 4ML"<CR><LF>
<FF>
Status Readback Commands 7-17