Spawn to the operating system. Type:
[n]Xronos> $[oper_sys_cmd]In particular:
[n]Xronos> $               !enter operating system; type `lo` (VMS) or `exit`
                            (UNIX) to return to Xronos
[n]Xronos> $ oper_sys_cmd  !execute operating system command `oper_sys_cmd`