The value of this variable is returned when an ACCEPT FROM INPUT STATUS
statement is executed on a machine that cannot determine the input status of the
terminal. This can be used to make a running program behave correctly on a new
machine. The value must be a single digit. The default value is "0".
If the input is redirected (not attached to a terminal), the SCRIPT_STATUS variable (later in this section) determines whether ACCEPT FROM INPUT
STATUS returns the value of the variable INPUT_STATUS_DEFAULT or returns the actual status of the input file.