<s>
Control-C	B-Device
is	O
a	O
common	O
computer	B-Application
command	I-Application
.	O
</s>
<s>
It	O
is	O
generated	O
by	O
pressing	O
the	O
key	O
while	O
holding	O
down	O
the	O
key	O
on	O
most	O
computer	B-Device
keyboards	I-Device
.	O
</s>
<s>
In	O
graphical	B-Application
user	I-Application
interface	I-Application
environments	O
that	O
use	O
the	O
control	B-Device
key	I-Device
to	O
control	O
the	O
active	O
program	O
,	O
control+C	O
is	O
often	O
used	O
to	O
copy	B-General_Concept
highlighted	O
text	O
to	O
the	O
clipboard	O
.	O
</s>
<s>
In	O
many	O
command-line	B-Application
interface	I-Application
environments	O
,	O
control+C	O
is	O
used	O
to	O
abort	B-General_Concept
the	O
current	O
task	O
and	O
regain	O
user	O
control	O
.	O
</s>
<s>
It	O
is	O
a	O
special	O
sequence	O
that	O
causes	O
the	O
operating	B-General_Concept
system	I-General_Concept
to	O
send	O
a	O
signal	B-Operating_System
to	O
the	O
active	O
program	O
.	O
</s>
<s>
Usually	O
the	O
signal	B-Operating_System
causes	O
it	O
to	O
end	O
,	O
but	O
the	O
program	O
may	O
"	O
catch	O
"	O
it	O
and	O
do	O
something	O
else	O
,	O
typically	O
returning	O
control	O
to	O
the	O
user	O
.	O
</s>
<s>
Larry	O
Tesler	O
created	O
the	O
concept	O
of	O
cut	B-General_Concept
,	I-General_Concept
copy	I-General_Concept
,	I-General_Concept
paste	I-General_Concept
,	I-General_Concept
and	I-General_Concept
undo	I-General_Concept
for	O
human-computer	O
interaction	O
while	O
working	O
at	O
Xerox	O
PARC	O
to	O
control	O
text	B-Application
editing	I-Application
.	O
</s>
<s>
During	O
the	O
development	O
of	O
the	O
Macintosh	B-Device
it	O
was	O
decided	O
that	O
the	O
cut	O
,	O
paste	O
,	O
copy	B-General_Concept
and	O
undo	O
would	O
be	O
used	O
frequently	O
and	O
assigned	O
them	O
to	O
the	O
⌘	B-Device
-Z	O
(	O
Undo	O
)	O
,	O
⌘	B-Device
-X	O
(	O
Cut	O
)	O
,	O
⌘	B-Device
-C	O
(	O
Copy	B-General_Concept
)	O
,	O
and	O
⌘	B-Device
-V	O
(	O
Paste	O
)	O
.	O
</s>
<s>
The	O
four	O
letters	O
are	O
all	O
located	O
together	O
at	O
the	O
left	O
end	O
of	O
the	O
bottom	O
row	O
of	O
the	O
standard	O
QWERTY	O
keyboard	B-Device
.	O
</s>
<s>
IBM	O
and	O
early	O
versions	O
of	O
windows	B-Application
used	O
a	O
different	O
set	O
of	O
keys	O
as	O
part	O
of	O
IBM	B-General_Concept
Common	I-General_Concept
User	I-General_Concept
Access	I-General_Concept
.	O
</s>
<s>
Later	O
versions	O
of	O
Windows	B-Application
adopted	O
the	O
shortcuts	O
using	O
Control	O
instead	O
of	O
the	O
Command	B-Device
key	I-Device
.	O
</s>
<s>
Control+C	O
was	O
part	O
of	O
various	O
Digital	O
Equipment	O
operating	B-General_Concept
systems	I-General_Concept
,	O
including	O
TOPS-10	B-Operating_System
and	O
TOPS-20	B-Operating_System
.	O
</s>
<s>
Its	O
popularity	O
as	O
an	O
abort	B-General_Concept
command	O
was	O
adopted	O
by	O
other	O
systems	O
including	O
Unix	B-Application
.	O
</s>
<s>
Later	O
systems	O
that	O
copied	O
it	O
include	O
CP/M	B-Application
,	O
DOS	B-Device
and	O
Windows	B-Application
.	O
</s>
<s>
In	O
POSIX	O
systems	O
,	O
the	O
sequence	O
causes	O
the	O
active	O
program	O
to	O
receive	O
SIGINT	B-General_Concept
,	O
the	O
interruption	O
signal	B-Operating_System
.	O
</s>
<s>
Typically	O
a	O
program	O
that	O
does	O
handle	O
a	O
SIGINT	B-General_Concept
will	O
still	O
terminate	O
itself	O
,	O
or	O
at	O
least	O
terminate	O
the	O
task	O
running	O
inside	O
it	O
.	O
</s>
<s>
This	O
system	O
is	O
usually	O
preserved	O
even	O
in	O
graphical	B-Application
terminal	B-Application
emulators	I-Application
.	O
</s>
<s>
If	O
control-C	B-Device
is	O
used	O
for	O
copy	B-General_Concept
in	O
the	O
graphical	B-Application
environment	I-Application
,	O
an	O
ambiguity	O
arises	O
.	O
</s>
<s>
As	O
many	O
keyboards	B-Device
and	O
computer	B-General_Concept
terminals	I-General_Concept
once	O
directly	O
generated	O
ASCII	B-Protocol
code	I-Protocol
,	O
the	O
choice	O
of	O
control+C	O
overlapped	O
with	O
the	O
ASCII	B-Protocol
end-of-text	O
character	O
.	O
</s>
