<s>
The	O
Page	B-Device
Up	I-Device
and	I-Device
Page	I-Device
Down	I-Device
keys	I-Device
(	O
sometimes	O
abbreviated	O
as	O
PgUp	B-Device
and	O
PgDn	B-Device
)	O
are	O
two	O
keys	O
commonly	O
found	O
on	O
computer	B-Device
keyboards	I-Device
.	O
</s>
<s>
The	O
arrow	B-Device
keys	I-Device
and	O
the	O
scroll	O
wheel	O
can	O
also	O
be	O
used	O
to	O
scroll	O
a	O
document	O
,	O
although	O
usually	O
by	O
smaller	O
incremental	O
distances	O
.	O
</s>
<s>
Used	O
together	O
with	O
a	O
modifier	B-Device
key	I-Device
,	O
such	O
as	O
,	O
,	O
or	O
a	O
combination	O
thereof	O
,	O
they	O
may	O
act	O
the	O
same	O
as	O
the	O
Page	O
keys	O
.	O
</s>
<s>
In	O
most	O
operating	O
systems	O
,	O
if	O
the	O
Page	B-Device
Up	I-Device
or	O
Page	B-Device
Down	I-Device
key	I-Device
is	O
pressed	O
along	O
with	O
the	O
key	O
in	O
editable	O
text	O
,	O
all	O
the	O
text	O
scrolled	O
over	O
will	O
be	O
highlighted	B-General_Concept
.	O
</s>
<s>
In	O
some	O
applications	O
,	O
the	O
and	O
keys	O
behave	O
differently	O
in	O
caret	B-Application
navigation	I-Application
(	O
toggled	O
with	O
the	O
function	O
key	O
in	O
Windows	O
)	O
.	O
</s>
<s>
In	O
August	O
2008	O
,	O
Microsoft	O
received	O
the	O
US	O
patent	O
#7	O
,	O
415,666	O
for	O
the	O
functions	O
of	O
the	O
two	O
keys	O
–	O
Page	B-Device
Up	I-Device
&	O
Page	B-Device
Down	I-Device
.	O
</s>
