NAME
        IoErr -- Return extra information from the system

    SYNOPSIS
        error = IoErr()
          D0

        long ioerr(void)

    FUNCTION
        Most I/O routines return zero to indicate an error. When this
        happens (or whatever the defined error return for the routine)
        this routine may be called to determine more information. It is
        also used in some routines to pass back a secondary result.

        Note: there is no guarantee as to the value returned from IoErr()
        after a successful operation, unless to specified by the routine.

    RESULTS
        error - integer

    SEE ALSO
        fault(), printfault(), setioerr()