<s>
Info	B-Protocol
is	O
a	O
software	B-Application
utility	I-Application
which	O
forms	O
a	O
hypertextual	O
,	O
multipage	O
documentation	O
and	O
help	B-Protocol
viewer	I-Protocol
working	O
on	O
a	O
command-line	B-Application
interface	I-Application
.	O
</s>
<s>
Info	B-Protocol
reads	O
info	B-Protocol
files	I-Protocol
generated	O
by	O
the	O
texinfo	B-Application
program	O
and	O
presents	O
the	O
documentation	O
as	O
a	O
tree	B-Data_Structure
with	O
simple	O
commands	O
to	O
traverse	O
the	O
tree	B-Data_Structure
and	O
to	O
follow	O
cross	O
references	O
.	O
</s>
<s>
For	O
instance	O
,	O
pressing	O
the	O
space	B-Device
bar	I-Device
scrolls	O
down	O
within	O
the	O
current	O
tree	B-Data_Structure
node	O
or	O
goes	O
to	O
the	O
next	O
node	O
in	O
the	O
current	O
document	O
if	O
already	O
at	O
the	O
bottom	O
of	O
the	O
current	O
node	O
,	O
allowing	O
to	O
read	O
the	O
contents	O
of	O
an	O
info	B-Protocol
file	I-Protocol
sequentially	O
.	O
</s>
<s>
Pressing	O
the	O
backspace	B-Device
key	I-Device
moves	O
in	O
the	O
opposite	O
direction	O
.	O
</s>
<s>
Moving	O
the	O
cursor	O
over	O
a	O
link	O
(	O
a	O
word	O
preceded	O
by	O
an	O
asterisk	O
)	O
and	O
pressing	O
the	O
enter	B-Device
key	I-Device
follows	O
the	O
link	O
.	O
</s>
<s>
The	O
C	B-Language
implementation	O
of	O
info	B-Protocol
was	O
designed	O
as	O
the	O
main	O
documentation	O
system	O
of	O
GNU	O
based	O
operating	B-General_Concept
systems	I-General_Concept
and	O
was	O
then	O
ported	O
to	O
other	O
Unix-like	B-Operating_System
operating	I-Operating_System
systems	I-Operating_System
.	O
</s>
<s>
However	O
,	O
info	B-Protocol
files	I-Protocol
had	O
already	O
been	O
in	O
use	O
on	O
ITS	B-Application
emacs	B-Application
.	O
</s>
<s>
On	O
the	O
TOPS-20	B-Operating_System
operating	B-General_Concept
system	I-General_Concept
INFO	B-Protocol
was	O
called	O
XINFO	O
.	O
</s>
