<s>
Each	O
version	O
of	O
the	O
UNIX	B-Application
Time-Sharing	O
System	O
evolved	O
from	O
the	O
version	O
before	O
,	O
with	O
version	O
one	O
evolving	O
from	O
the	O
prototypal	O
Unix	B-Application
.	O
</s>
<s>
The	O
versions	O
leading	O
to	O
v7	O
are	O
also	O
sometimes	O
called	O
Ancient	B-Operating_System
unix	I-Operating_System
.	O
</s>
<s>
After	O
the	O
release	O
of	O
Version	O
10	O
,	O
the	O
Unix	B-Application
research	O
team	O
at	O
Bell	O
Labs	O
turned	O
its	O
focus	O
to	O
Plan	B-Operating_System
9	I-Operating_System
from	I-Operating_System
Bell	I-Operating_System
Labs	I-Operating_System
,	O
a	O
distinct	O
operating	O
system	O
that	O
was	O
first	O
released	O
to	O
the	O
public	O
in	O
1993	O
.	O
</s>
<s>
Each	O
of	O
the	O
systems	O
in	O
this	O
list	O
is	O
evolved	O
from	O
the	O
version	O
before	O
,	O
with	O
Unix	B-Operating_System
System	I-Operating_System
III	I-Operating_System
evolving	O
from	O
both	O
the	O
UNIX	B-Operating_System
Time-Sharing	I-Operating_System
System	I-Operating_System
v7	I-Operating_System
and	O
the	O
descendants	O
of	O
the	O
UNIX	B-Operating_System
Time-Sharing	I-Operating_System
System	I-Operating_System
v6	I-Operating_System
.	O
</s>
