<s>
The	O
Xerox	B-Operating_System
Operating	I-Operating_System
System	I-Operating_System
(	O
XOS	O
)	O
was	O
an	O
operating	O
system	O
for	O
the	O
XDS	O
Sigma	B-Device
series	I-Device
of	O
computers	O
"	O
optimized	O
for	O
direct	O
replacement	O
of	O
IBM	O
DOS/360	B-Application
installations	O
"	O
and	O
to	O
provide	O
real-time	B-Operating_System
and	O
timesharing	B-General_Concept
support	O
.	O
</s>
