Lexmark J110 Reference Manual page 200

dostartpage
returns a boolean with the same value as the system parameter DoStartPage.
The DoStartPage system parameter must be present for the compatibility
operator dostartpage to be present.
Error: stackoverflow
dosysstart
returns the current value of the StartupMode system parameter. A boolean
value is returned:
StartupMode set to 1 or 11
StartupMode other than 1 or 11
This operator is equivalent to executing the following PostScript emulation
sequence:
currentsystemsparams /StartupMode get
Error: stackoverflow
duplexer
queries if a duplex unit is installed. A boolean value is returned on the stack:
duplex unit is installed
duplex unit is not installed
Note: For printers that do not support duplexing, this value is always
Error: stackoverflow
4-33
PostScript
.