Lexmark C520 Technical Reference page 243

userdiskpercent
— userdiskpercent 0
returns a (zero) on the stack.
0
Errors: stackoverflow, invalidaccess
waittimeout
— waittimeout integer
queries the current value for the WaitTimeout user parameter. An integer is
returned on the stack:
disabled
0
seconds
15...65355
This operator is equivalent to executing the following PostScript emulation
sequence:
currentuserparams /WaitTimeout get
Error: stackoverflow
4-48
PostScript