<s>
In	O
computing	O
,	O
a	O
modifier	B-Device
key	I-Device
is	O
a	O
special	O
key	O
(	O
or	O
combination	O
)	O
on	O
a	O
computer	B-Device
keyboard	I-Device
that	O
temporarily	O
modifies	O
the	O
normal	O
action	O
of	O
another	O
key	O
when	O
pressed	O
together	O
.	O
</s>
<s>
By	O
themselves	O
,	O
modifier	B-Device
keys	I-Device
usually	O
do	O
nothing	O
;	O
that	O
is	O
,	O
pressing	O
any	O
of	O
the	O
,	O
,	O
or	O
keys	O
alone	O
does	O
not	O
(	O
generally	O
)	O
trigger	O
any	O
action	O
from	O
the	O
computer	O
.	O
</s>
<s>
For	O
example	O
,	O
in	O
most	O
keyboard	B-Device
layouts	O
the	O
Shift	B-Device
key	I-Device
combination	O
will	O
produce	O
a	O
capital	O
letter	O
"	O
A	O
"	O
instead	O
of	O
the	O
default	O
lower-case	O
letter	O
"	O
a	O
"	O
(	O
unless	O
in	O
Caps	B-Device
lock	I-Device
or	O
Shift	B-Device
lock	O
mode	O
)	O
.	O
</s>
<s>
A	O
combination	O
of	O
in	O
Microsoft	B-Application
Windows	I-Application
will	O
close	O
the	O
active	O
window	O
;	O
in	O
this	O
instance	O
,	O
Alt	B-Device
is	O
the	O
modifier	B-Device
key	I-Device
.	O
</s>
<s>
User	B-Application
interface	I-Application
expert	O
Jef	O
Raskin	O
coined	O
the	O
term	O
"	O
quasimode	B-General_Concept
"	O
to	O
describe	O
the	O
state	O
a	O
computer	O
enters	O
into	O
when	O
a	O
modifier	B-Device
key	I-Device
is	O
pressed	O
.	O
</s>
<s>
(	O
Alternate	O
)	O
–	O
also	O
labelled	O
on	O
Apple	B-Device
keyboards	I-Device
.	O
</s>
<s>
–	O
Meta	B-Device
key	I-Device
,	O
found	O
on	O
MIT	O
,	O
Symbolics	O
,	O
and	O
Sun	O
Microsystems	O
keyboards	B-Device
.	O
</s>
<s>
–	O
Super	B-Device
key	I-Device
,	O
found	O
on	O
MIT	O
,	O
Symbolics	O
,	O
Linux	O
,	O
and	O
BSD	O
keyboards	B-Device
.	O
</s>
<s>
(	O
Windows	O
logo	O
)	O
–	O
found	O
on	O
Windows	O
keyboards	B-Device
.	O
</s>
<s>
–	O
Command	O
key	O
,	O
found	O
on	O
Apple	B-Device
keyboards	I-Device
.	O
</s>
<s>
On	O
older	O
keyboards	B-Device
labelled	O
(	O
Apple	O
logo	O
)	O
.	O
</s>
<s>
(	O
Function	O
)	O
–	O
often	O
present	O
on	O
small-layout	O
keyboards	B-Device
,	O
or	O
keyboard	B-Device
where	O
the	O
top	O
row	O
of	O
function	B-Application
keys	I-Application
have	O
multimedia	O
functions	O
like	O
controlling	O
volume	O
attached	O
.	O
</s>
<s>
The	O
(	O
Sun	O
)	O
Meta	B-Device
key	I-Device
,	O
Windows	O
key	O
,	O
(	O
Apple	O
)	O
Cmd	O
key	O
,	O
and	O
the	O
analogous	O
"	O
Amiga	B-Device
key	I-Device
"	O
(	O
)	O
on	O
Amiga	B-Device
computers	I-Device
,	O
are	O
usually	O
handled	O
equivalently	O
.	O
</s>
<s>
Under	O
the	O
Linux	O
operating	O
system	O
,	O
the	O
desktop	O
environment	O
KDE	B-Application
calls	O
this	O
key	O
Meta	B-Device
,	O
while	O
GNOME	B-Application
calls	O
this	O
key	O
,	O
neutrally	O
,	O
Super	B-Device
.	O
</s>
<s>
(	O
This	O
is	O
a	O
bit	O
confusing	O
,	O
since	O
the	O
original	O
space-cadet	B-Device
keyboard	I-Device
and	O
the	O
X	B-Operating_System
Window	I-Operating_System
System	I-Operating_System
recognize	O
a	O
""	O
modifier	O
distinct	O
from	O
""	O
.	O
)	O
</s>
<s>
The	O
ZX	B-Operating_System
Spectrum	I-Operating_System
has	O
a	O
Symbol	O
Shift	B-Device
key	I-Device
in	O
addition	O
to	O
Caps	O
Shift	B-Device
.	O
</s>
<s>
The	O
MSX	B-Operating_System
computer	B-Device
keyboard	I-Device
,	O
besides	O
Shift	B-Device
and	O
Control	O
,	O
also	O
included	O
two	O
special	O
modifier	B-Device
keys	I-Device
,	O
Code	O
and	O
Graph	O
.	O
</s>
<s>
In	O
some	O
models	O
,	O
as	O
in	O
the	O
Brazilian	O
Gradiente	B-Device
Expert	I-Device
,	O
the	O
Code	O
and	O
Graph	O
keys	O
are	O
labelled	O
""	O
and	O
""	O
(	O
Left	O
and	O
Right	O
Graphics	O
)	O
.	O
</s>
<s>
Likewise	O
,	O
the	O
Commodore	O
64	O
and	O
other	O
Commodore	O
computers	O
had	O
the	O
Commodore	B-Device
key	I-Device
at	O
the	O
bottom	O
left	O
of	O
the	O
keyboard	B-Device
.	O
</s>
<s>
Compact	O
keyboards	B-Device
,	O
such	O
as	O
those	O
used	O
in	O
laptops	B-Device
,	O
often	O
have	O
a	O
Fn	B-Device
key	I-Device
to	O
save	O
space	O
by	O
combining	O
two	O
functions	O
that	O
are	O
normally	O
on	O
separate	O
keys	O
.	O
</s>
<s>
On	O
laptops	B-Device
,	O
pressing	O
plus	O
one	O
of	O
the	O
function	B-Application
keys	I-Application
,	O
e.g.	O
,	O
F2	O
,	O
often	O
control	O
hardware	O
functions	O
.	O
</s>
<s>
Keyboards	B-Device
that	O
lack	O
a	O
dedicated	O
numeric	O
keypad	O
may	O
mimic	O
its	O
functionality	O
by	O
combining	O
the	O
Fn	B-Device
key	I-Device
with	O
other	O
keys	O
.	O
</s>
<s>
The	O
MIT	O
space-cadet	B-Device
keyboard	I-Device
had	O
additional	O
Top	O
and	O
Front	O
modifier	B-Device
keys	I-Device
.	O
</s>
<s>
Specialist	O
typesetting	O
machines	O
,	O
and	O
word	O
processors	O
such	O
as	O
the	O
Redactron	O
,	O
sometimes	O
used	O
multiple	O
modifier	B-Device
keys	I-Device
to	O
trigger	O
mode	O
changes	O
e.g.	O
</s>
<s>
This	O
approach	O
gradually	O
became	O
obsolete	O
after	O
software	O
based	O
on	O
commodity	O
hardware	O
and	O
operating	O
systems	O
adopted	O
the	O
WIMP	B-Application
metaphor	O
which	O
provided	O
drop-down	O
menus	O
etc	O
.	O
</s>
<s>
Some	O
non-English	O
language	O
keyboards	B-Device
have	O
special	O
keys	O
to	O
produce	O
accented	O
modifications	O
of	O
the	O
standard	O
Latin-letter	O
keys	O
.	O
</s>
<s>
In	O
fact	O
,	O
the	O
standard	O
British	O
keyboard	B-Device
layout	O
includes	O
an	O
accent	O
key	O
on	O
the	O
top-left	O
corner	O
to	O
produce	O
àèìòù	O
,	O
although	O
this	O
is	O
a	O
two	O
step	O
procedure	O
,	O
with	O
the	O
user	O
pressing	O
the	O
accent	O
key	O
,	O
releasing	O
,	O
then	O
pressing	O
the	O
letter	O
key	O
.	O
</s>
<s>
These	O
kinds	O
of	O
keys	O
are	O
called	O
dead	B-Device
keys	I-Device
.	O
</s>
<s>
The	O
AltGr	B-Device
modifier	O
produces	O
the	O
áéíóú	O
sequence	O
,	O
or	O
in	O
conjunction	O
with	O
the	O
Shift	B-Device
key	I-Device
,	O
ÁÉÍÓÚ	O
.	O
</s>
<s>
Keyboards	B-Device
of	O
some	O
languages	O
simply	O
include	O
the	O
accented	O
characters	O
on	O
their	O
own	O
keys	O
.	O
</s>
<s>
Some	O
keyboards	B-Device
also	O
have	O
a	O
Compose	B-Device
key	I-Device
for	O
typing	O
accented	O
and	O
other	O
special	O
characters	O
.	O
</s>
<s>
For	O
example	O
,	O
you	O
can	O
use	O
the	O
both	O
as	O
a	O
normal	O
Space	O
bar	O
and	O
as	O
a	O
Shift	B-Device
.	O
</s>
<s>
Intuitively	O
,	O
it	O
will	O
act	O
as	O
a	O
standard	O
Space	O
when	O
you	O
want	O
a	O
whitespace	O
,	O
and	O
a	O
Shift	B-Device
when	O
you	O
want	O
it	O
to	O
act	O
as	O
a	O
shift	B-Device
.	O
</s>
<s>
when	O
you	O
simply	O
press	O
and	O
release	O
it	O
,	O
it	O
is	O
the	O
usual	O
space	O
,	O
but	O
when	O
you	O
press	O
other	O
keys	O
,	O
say	O
,	O
and	O
,	O
while	O
holding	O
down	O
the	O
,	O
then	O
they	O
will	O
be	O
treated	O
as	O
plus	O
X	B-Operating_System
,	O
Y	O
and	O
Z	O
.	O
</s>
<s>
The	O
above	O
example	O
is	O
known	O
as	O
"	O
SandS	O
"	O
,	O
standing	O
for	O
"	O
Space	O
and	O
Shift	B-Device
"	O
in	O
Japan	O
.	O
</s>
<s>
To	O
press	O
shift+space	O
in	O
the	O
previous	O
example	O
,	O
you	O
need	O
in	O
addition	O
to	O
a	O
space/shift	O
dual	O
role	O
key	O
,	O
one	O
of	O
(	O
a	O
)	O
another	O
space/shift	O
key	O
,	O
(	O
b	O
)	O
a	O
usual	O
shift	B-Device
,	O
or	O
(	O
c	O
)	O
a	O
usual	O
space	O
key	O
.	O
</s>
