<s>
In	O
the	O
field	O
of	O
user	B-Application
interfaces	I-Application
,	O
an	O
exocentric	B-Application
environment	I-Application
refers	O
to	O
a	O
virtual	B-Application
reality	I-Application
or	O
some	O
other	O
immersive	O
environment	O
which	O
completely	O
encompasses	O
the	O
user	O
,	O
e.g.	O
</s>
<s>
by	O
placing	O
the	O
viewer	O
in	O
a	O
room	O
made	O
up	O
entirely	O
of	O
rear	B-Device
projection	I-Device
screens	I-Device
.	O
</s>
<s>
Systems	O
which	O
merely	O
display	O
a	O
virtual	B-Application
reality	I-Application
directly	O
to	O
the	O
user	O
(	O
e.g.	O
</s>
<s>
They	O
are	O
endocentric	B-General_Concept
environments	I-General_Concept
.	O
</s>
