| Bit | Meaning when set |
|---|---|
| 0 | Do not display restart dialog window |
| 1 | Do not broadcast Message_PreQuit |
| 2 | Set flag in CMOS as portable PowerDown |
| 3 | Send a Message_Shutdown |
| 4 | Reject OS_UpCall 1 & 2 reason codes |
| 5 | Reboot machine once shutdown is complete1 |
| 6-31 | Must be 0 |
1 RISC OS 4.01 onwards
If bit 2 is set, then it is flagged in CMOS that the last shutdown was forced by a low battery, and a message stating this reason will be displayed upon next Desktop start.