<s>
In	O
computing	O
,	O
a	O
Control	B-Device
key	I-Device
is	O
a	O
modifier	B-Device
key	I-Device
which	O
,	O
when	O
pressed	O
in	O
conjunction	O
with	O
another	O
key	O
,	O
performs	O
a	O
special	O
operation	O
(	O
for	O
example	O
,	O
)	O
.	O
</s>
<s>
Similarly	O
to	O
the	O
Shift	B-Device
key	I-Device
,	O
the	O
Control	B-Device
key	I-Device
rarely	O
performs	O
any	O
function	O
when	O
pressed	O
by	O
itself	O
.	O
</s>
<s>
The	O
Control	B-Device
key	I-Device
is	O
located	O
on	O
or	O
near	O
the	O
bottom	O
left	O
side	O
of	O
most	O
keyboards	B-Device
(	O
in	O
accordance	O
with	O
the	O
international	O
standard	O
ISO/IEC	O
9995-2	O
)	O
,	O
with	O
many	O
featuring	O
an	O
additional	O
one	O
at	O
the	O
bottom	O
right	O
.	O
</s>
<s>
On	O
keyboards	B-Device
that	O
use	O
English	O
abbreviations	O
for	O
key	O
labeling	O
,	O
it	O
is	O
usually	O
labeled	O
(	O
rarely	O
,	O
or	O
is	O
seen	O
)	O
.	O
</s>
<s>
Abbreviations	O
in	O
the	O
language	O
of	O
the	O
keyboard	B-Device
layout	O
also	O
are	O
in	O
use	O
,	O
e.g.	O
,	O
the	O
German	O
keyboard	B-Device
layout	O
uses	O
as	O
required	O
by	O
the	O
German	O
standard	O
DIN	B-Application
2137:2012-06	O
.	O
</s>
<s>
Also	O
,	O
there	O
is	O
a	O
standardized	O
keyboard	B-Device
symbol	O
(	O
to	O
be	O
used	O
when	O
Latin	O
lettering	O
is	O
not	O
preferred	O
)	O
,	O
given	O
in	O
ISO/IEC	O
9995-7	O
as	O
symbol	O
26	O
,	O
and	O
in	O
ISO	O
7000	O
"	O
Graphical	O
symbols	O
for	O
use	O
on	O
equipment	O
"	O
as	O
symbol	O
ISO-7000-2028	O
.	O
</s>
<s>
This	O
symbol	O
is	O
encoded	O
in	O
Unicode	O
as	O
U+2388	O
( ⎈	O
)	O
.	O
</s>
<s>
On	O
teletypewriters	O
and	O
computer	B-General_Concept
terminals	I-General_Concept
,	O
holding	O
down	O
the	O
Control	B-Device
key	I-Device
while	O
pressing	O
another	O
key	O
would	O
send	O
an	O
ASCII	B-Protocol
C0	O
control	O
character	O
,	O
instead	O
of	O
directly	O
reporting	O
a	O
key	O
press	O
to	O
the	O
system	O
.	O
</s>
<s>
The	O
first	O
32	O
ASCII	B-Protocol
characters	I-Protocol
are	O
the	O
control	O
characters	O
,	O
representable	O
by	O
a	O
5-bit	O
binary	O
number	O
.	O
</s>
<s>
Because	O
ASCII	B-Protocol
characters	I-Protocol
were	O
represented	O
as	O
7	O
bits	O
,	O
if	O
a	O
key	O
is	O
pressed	O
while	O
the	O
Control	B-Device
key	I-Device
was	O
held	O
down	O
,	O
teletypewriters	O
and	O
terminals	O
would	O
simply	O
set	O
the	O
first	O
2	O
bits	O
of	O
a	O
character	O
to	O
0	O
,	O
converting	O
the	O
character	O
into	O
a	O
control	O
character	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
character	O
"	O
a	O
"	O
has	O
a	O
binary	B-Protocol
ASCII	I-Protocol
code	O
of	O
110	O
0001	O
.	O
</s>
<s>
This	O
code	O
would	O
be	O
converted	O
to	O
000	O
0001	O
,	O
corresponding	O
to	O
the	O
ASCII	B-Protocol
character	I-Protocol
with	O
id	O
1	O
(	O
the	O
SOH	O
Character	O
)	O
.	O
</s>
<s>
The	O
table	O
at	O
shows	O
the	O
ASCII	B-Protocol
control	O
characters	O
,	O
with	O
the	O
"	O
Caret	O
notation	O
"	O
column	O
showing	O
a	O
caret	O
( ^	O
)	O
,	O
followed	O
by	O
the	O
character	O
to	O
press	O
while	O
the	O
Control	B-Device
key	I-Device
is	O
held	O
down	O
to	O
generate	O
the	O
character	O
.	O
</s>
<s>
For	O
example	O
,	O
Control-C	B-Device
,	O
received	O
from	O
a	O
teletypewriter	O
or	O
terminal	O
,	O
is	O
interpreted	O
as	O
"	O
interrupt	O
the	O
current	O
program	O
"	O
in	O
some	O
command-line	B-Application
interfaces	I-Application
,	O
and	O
Control-E	O
is	O
interpreted	O
by	O
the	O
Emacs	B-Application
text	O
editor	O
as	O
"	O
move	O
the	O
editor	O
cursor	O
to	O
the	O
end	O
of	O
the	O
line	O
"	O
.	O
</s>
<s>
Computer	B-Device
keyboards	I-Device
directly	O
attached	O
to	O
a	O
computer	O
,	O
as	O
is	O
the	O
case	O
for	O
a	O
personal	B-Device
computer	I-Device
or	O
workstation	B-Device
,	O
distinguish	O
each	O
physical	O
key	O
from	O
every	O
other	O
and	O
report	O
all	O
keypresses	O
and	O
releases	O
to	O
the	O
controlling	O
software	O
.	O
</s>
<s>
This	O
allows	O
the	O
software	O
to	O
interpret	O
Control	B-Device
key	I-Device
combinations	O
as	O
it	O
chooses	O
,	O
including	O
being	O
able	O
to	O
interpret	O
a	O
combination	O
of	O
the	O
Control	B-Device
key	I-Device
,	O
another	O
modifier	B-Device
key	I-Device
,	O
and	O
a	O
letter	O
,	O
number	O
,	O
or	O
symbol	O
key	O
differently	O
from	O
the	O
way	O
it	O
interprets	O
a	O
combination	O
of	O
the	O
Control	B-Device
key	I-Device
and	O
the	O
letter	O
,	O
number	O
,	O
or	O
symbol	O
key	O
without	O
that	O
other	O
modifier	B-Device
key	I-Device
.	O
</s>
<s>
The	O
keyboards	B-Device
of	O
many	O
early	O
computer	B-General_Concept
terminals	I-General_Concept
,	O
including	O
the	O
Teletype	B-Application
Model	I-Application
33	I-Application
ASR	O
and	O
Lear-Siegler	O
ADM-3A	B-Device
,	O
and	O
early	O
models	O
of	O
the	O
IBM	B-Device
PC	I-Device
,	O
positioned	O
the	O
Control	B-Device
key	I-Device
on	O
the	O
left	O
of	O
the	O
keyboard	B-Device
,	O
whereas	O
caps	B-Device
lock	I-Device
resides	O
in	O
the	O
same	O
position	O
on	O
most	O
modern	O
keyboards	B-Device
.	O
</s>
<s>
The	O
traditional	O
layout	O
was	O
preserved	O
for	O
later	O
workstation	B-Device
systems	O
and	O
is	O
often	O
associated	O
with	O
Unix	B-Device
workstations	I-Device
.	O
</s>
<s>
Keyboards	B-Device
from	O
Sun	O
Microsystems	O
came	O
in	O
two	O
layouts	O
;	O
"	O
Unix	B-Application
"	O
and	O
"	O
PC-style	O
"	O
,	O
with	O
the	O
Unix	B-Application
layout	O
having	O
the	O
traditional	O
placing	O
of	O
the	O
Control	B-Device
key	I-Device
and	O
other	O
keys	O
.	O
</s>
<s>
The	O
keyboards	B-Device
produced	O
for	O
One	O
Laptop	O
Per	O
Child	O
computers	O
also	O
have	O
the	O
Control	B-Device
key	I-Device
in	O
this	O
location	O
.	O
</s>
<s>
Other	O
vendors	O
produce	O
keyboards	B-Device
for	O
different	O
computer	O
systems	O
with	O
this	O
placement	O
of	O
the	O
Control	B-Device
key	I-Device
,	O
such	O
as	O
the	O
Happy	B-Device
Hacking	I-Device
Keyboard	I-Device
.	O
</s>
<s>
Some	O
users	O
of	O
keyboards	B-Device
with	O
caps	B-Device
lock	I-Device
on	O
the	O
left	O
remap	O
the	O
keys	O
to	O
exchange	O
Control	O
and	O
caps	B-Device
lock	I-Device
,	O
finding	O
the	O
traditional	O
location	O
more	O
ergonomic	O
for	O
using	O
programs	O
benefiting	O
from	O
use	O
of	O
the	O
Control	B-Device
key	I-Device
.	O
</s>
<s>
Keyboard	B-Device
layout	O
preferences	O
specifically	O
to	O
address	O
this	O
need	O
are	O
available	O
in	O
some	O
operating	O
systems	O
.	O
</s>
<s>
Others	O
leave	O
the	O
control	B-Device
key	I-Device
in	O
the	O
lower-left	O
corner	O
of	O
the	O
keyboard	B-Device
,	O
and	O
press	O
it	O
using	O
the	O
side	O
of	O
their	O
palm	O
.	O
</s>
<s>
The	O
choice	O
of	O
location	O
for	O
the	O
control	B-Device
key	I-Device
often	O
comes	O
down	O
to	O
the	O
typist	O
's	O
hand	O
shape	O
and	O
posture	O
.	O
</s>
<s>
There	O
are	O
several	O
common	O
notations	O
for	O
pressing	O
the	O
Control	B-Device
key	I-Device
in	O
conjunction	O
with	O
another	O
key	O
.	O
</s>
<s>
Different	O
application	O
programs	O
,	O
user	O
interfaces	O
,	O
and	O
operating	O
systems	O
use	O
the	O
various	O
control	B-Device
key	I-Device
combinations	O
for	O
different	O
purposes	O
.	O
</s>
<s>
Key	O
combinationMicrosoft	O
Windows/KDE/GNOMEUnix	O
(	O
command	B-Application
line	I-Application
and	O
programs	O
using	O
readline	B-Application
)	O
Emacs	B-Application
(	O
if	O
different	O
from	O
Unix	B-Application
command	B-Application
line	I-Application
)	O
Select	O
all	O
Beginning	O
of	O
line	O
Bold	O
Backward	O
one	O
character	O
Copy	B-General_Concept
Generate	O
SIGINT	B-General_Concept
(	O
terminate	O
program	O
)	O
Compound	O
command	O
Font	O
window	O
(	O
word	O
processing	O
)	O
;	O
Add	O
to	O
bookmarks	O
(	O
Browsers	B-Application
)	O
Forward	O
delete	O
,	O
or	O
if	O
line	O
is	O
empty	O
,	O
end	O
of	O
input	O
(	O
traditional	B-Application
Unix	I-Application
)	O
Forward	O
delete	O
Center	O
alignment	O
(	O
word	O
processing	O
)	O
End	O
of	O
line	O
Find	O
(	O
usually	O
a	O
small	O
piece	O
of	O
text	O
in	O
a	O
larger	O
document	O
)	O
Forward	O
one	O
character	O
Go	O
to	O
(	O
line	O
number	O
)	O
Abort	O
current	O
operation	O
Replace	O
;	O
History	O
Delete	O
previous	O
character	O
Help	O
key	O
Italic	O
;	O
Incremental	O
search	O
Command-line	B-Application
completion	O
(	O
same	O
as	O
Tab	O
key	O
)	O
Justify	O
Line	O
feed	O
(	O
LFD	O
)	O
LFD	O
(	O
to	O
evaluate	O
Lisp	B-Language
expressions	O
)	O
Insert	O
hyperlink	O
(	O
word	O
processing	O
)	O
Cut	B-General_Concept
(	O
"	O
Kill	O
"	O
)	O
text	O
between	O
cursor	O
and	O
end	O
of	O
line	O
Create	O
list	O
;	O
Left	O
align	O
(	O
word	O
processing	O
)	O
Clear	O
screen	O
Redraw	O
window/terminal	O
,	O
and	O
recenter	O
view	O
around	O
current	O
line	O
Increase	O
margin	O
by	O
1/2	O
inch	O
(	O
word	O
processing	O
)	O
Same	O
as	O
Enter	B-Device
key	I-Device
New	O
(	O
window	O
,	O
document	O
,	O
etc	O
.	O
)	O
</s>
<s>
In	O
early	O
first-person	O
shooters	O
,	O
the	O
left	O
Ctrl	B-Device
key	I-Device
is	O
often	O
used	O
to	O
fire	O
a	O
weapon	O
.	O
</s>
<s>
Generally	O
,	O
the	O
Command	B-Device
key	I-Device
,	O
labeled	O
with	O
the	O
⌘	O
symbol	O
on	O
Apple	B-Device
Macintosh	I-Device
computers	I-Device
,	O
performs	O
the	O
equivalent	O
functions	O
in	O
classic	B-Application
Mac	I-Application
OS	I-Application
and	O
macOS	B-Application
applications	O
(	O
for	O
example	O
,	O
copies	O
,	O
while	O
prints	O
;	O
the	O
same	O
holds	O
for	O
saving	O
,	O
cutting	O
,	O
and	O
pasting	O
)	O
.	O
</s>
<s>
Macintoshes	B-Device
also	O
have	O
a	O
Control	B-Device
key	I-Device
,	O
but	O
it	O
has	O
different	O
functionality	O
.	O
</s>
<s>
On	O
Unix	B-Application
and	O
Windows	O
,	O
the	O
user	O
had	O
other	O
mouse	O
buttons	O
to	O
use	O
.	O
</s>
<s>
On	O
Classic	B-Application
Mac	I-Application
OS	I-Application
and	O
macOS	B-Application
,	O
the	O
Control	B-Device
key	I-Device
is	O
used	O
to	O
invoke	O
a	O
"	O
right-click	O
"	O
.	O
</s>
<s>
It	O
is	O
mostly	O
used	O
as	O
a	O
modifier	B-Device
key	I-Device
for	O
key-combinations	O
.	O
</s>
<s>
It	O
is	O
used	O
in	O
the	O
command	B-Application
line	I-Application
interface	I-Application
with	O
programs	O
made	O
for	O
that	O
interface	O
.	O
</s>
<s>
In	O
Quickbooks	B-Application
,	O
the	O
Control	B-Device
Key	I-Device
is	O
used	O
to	O
validate	O
login	O
credentials	O
during	O
OLSU	O
1016	O
and	O
OLSU	O
1013	O
errors	O
.	O
</s>
<s>
Keeping	O
it	O
depressed	O
while	O
sending	O
information	O
to	O
the	O
Quickbooks	B-Application
servers	O
fixes	O
the	O
errors	O
.	O
</s>
<s>
Under	O
macOS	B-Application
,	O
the	O
Control	B-Device
key	I-Device
allows	O
the	O
use	O
of	O
Emacs-style	O
key	O
combinations	O
in	O
most	O
text	O
entry	O
fields	O
.	O
</s>
<s>
For	O
example	O
,	O
Ctrl-A	O
moves	O
the	O
caret	O
to	O
the	O
start	O
of	O
the	O
paragraph	O
,	O
Ctrl-L	O
vertically	O
centers	O
the	O
current	O
line	O
in	O
the	O
editing	O
field	O
,	O
Ctrl-K	O
cuts	O
text	O
to	O
the	O
end	O
of	O
the	O
line	O
to	O
a	O
kill	O
ring	O
separate	O
from	O
the	O
normal	O
clipboard	O
,	O
etc	O
.	O
</s>
