<s>
In	O
computing	O
and	O
telecommunication	O
,	O
an	O
escape	B-Algorithm
character	I-Algorithm
is	O
a	O
character	O
that	O
invokes	O
an	O
alternative	O
interpretation	O
on	O
the	O
following	O
characters	O
in	O
a	O
character	O
sequence	O
.	O
</s>
<s>
An	O
escape	B-Algorithm
character	I-Algorithm
is	O
a	O
particular	O
case	O
of	O
metacharacters	B-Algorithm
.	O
</s>
<s>
Generally	O
,	O
the	O
judgement	O
of	O
whether	O
something	O
is	O
an	O
escape	B-Algorithm
character	I-Algorithm
or	O
not	O
depends	O
on	O
the	O
context	O
.	O
</s>
<s>
In	O
the	O
telecommunications	O
field	O
,	O
escape	B-Algorithm
characters	I-Algorithm
are	O
used	O
to	O
indicate	O
that	O
the	O
following	O
characters	O
are	O
encoded	O
differently	O
.	O
</s>
<s>
In	O
this	O
context	O
,	O
the	O
use	O
of	O
escape	B-Algorithm
characters	I-Algorithm
is	O
often	O
referred	O
to	O
as	O
quoting	B-Language
.	O
</s>
<s>
An	O
escape	B-Algorithm
character	I-Algorithm
may	O
not	O
have	O
its	O
own	O
meaning	O
,	O
so	O
all	O
escape	O
sequences	O
are	O
of	O
two	O
or	O
more	O
characters	O
.	O
</s>
<s>
Escape	B-Algorithm
characters	I-Algorithm
are	O
part	O
of	O
the	O
syntax	O
for	O
many	O
programming	O
languages	O
,	O
data	O
formats	O
,	O
and	O
communication	O
protocols	O
.	O
</s>
<s>
For	O
a	O
given	O
alphabet	O
an	O
escape	B-Algorithm
character	I-Algorithm
's	O
purpose	O
is	O
to	O
start	O
character	O
sequences	O
(	O
so	O
named	O
escape	O
sequences	O
)	O
,	O
which	O
have	O
to	O
be	O
interpreted	O
differently	O
from	O
the	O
same	O
characters	O
occurring	O
without	O
the	O
prefixed	O
escape	B-Algorithm
character	I-Algorithm
.	O
</s>
<s>
To	O
represent	O
characters	O
,	O
referred	O
to	O
as	O
character	O
quoting	B-Language
,	O
which	O
cannot	O
be	O
typed	O
in	O
the	O
current	O
context	O
,	O
or	O
would	O
have	O
an	O
undesired	O
interpretation	O
.	O
</s>
<s>
In	O
this	O
case	O
,	O
an	O
escape	O
sequence	O
is	O
a	O
digraph	B-Language
consisting	O
of	O
an	O
escape	B-Algorithm
character	I-Algorithm
itself	O
and	O
a	O
"	O
quoted	O
"	O
character	O
.	O
</s>
<s>
Generally	O
,	O
an	O
escape	B-Algorithm
character	I-Algorithm
is	O
not	O
a	O
particular	O
case	O
of	O
(	O
device	O
)	O
control	O
characters	O
,	O
nor	O
vice	O
versa	O
.	O
</s>
<s>
printer	O
or	O
text	O
terminal	O
)	O
then	O
any	O
escape	B-Algorithm
character	I-Algorithm
for	O
this	O
device	O
is	O
a	O
control	O
one	O
.	O
</s>
<s>
But	O
escape	B-Algorithm
characters	I-Algorithm
used	O
in	O
programming	O
(	O
such	O
as	O
the	O
backslash	O
,	O
"	O
\	O
 "	O
)	O
are	O
graphic	O
,	O
hence	O
are	O
not	O
control	O
characters	O
.	O
</s>
<s>
Conversely	O
most	O
(	O
but	O
not	O
all	O
)	O
of	O
the	O
ASCII	B-Protocol
"	O
control	O
characters	O
"	O
have	O
some	O
control	O
function	O
in	O
isolation	O
,	O
therefore	O
they	O
are	O
not	O
escape	B-Algorithm
characters	I-Algorithm
.	O
</s>
<s>
In	O
many	O
programming	O
languages	O
,	O
an	O
escape	B-Algorithm
character	I-Algorithm
also	O
forms	O
some	O
escape	O
sequences	O
which	O
are	O
referred	O
to	O
as	O
control	O
characters	O
.	O
</s>
<s>
JavaScript	O
uses	O
the	O
(	O
backslash	O
)	O
as	O
an	O
escape	B-Algorithm
character	I-Algorithm
for	O
:	O
</s>
<s>
vertical	O
tab	O
(	O
Internet	B-Application
Explorer	I-Application
9	I-Application
and	O
older	O
treats	O
as	O
instead	O
of	O
a	O
vertical	O
tab	O
(	O
)	O
.	O
</s>
<s>
The	O
ASCII	B-Protocol
"	O
escape	O
"	O
character	O
(	O
octal	O
:	O
,	O
hexadecimal	O
:	O
,	O
or	O
,	O
or	O
,	O
in	O
decimal	O
,	O
)	O
is	O
used	O
in	O
many	O
output	O
devices	O
to	O
start	O
a	O
series	O
of	O
characters	O
called	O
a	O
control	O
sequence	O
or	O
escape	O
sequence	O
.	O
</s>
<s>
Typically	O
,	O
the	O
escape	B-Algorithm
character	I-Algorithm
was	O
sent	O
first	O
in	O
such	O
a	O
sequence	O
to	O
alert	O
the	O
device	O
that	O
the	O
following	O
characters	O
were	O
to	O
be	O
interpreted	O
as	O
a	O
control	O
sequence	O
rather	O
than	O
as	O
plain	O
characters	O
,	O
then	O
one	O
or	O
more	O
characters	O
would	O
follow	O
to	O
specify	O
some	O
detailed	O
action	O
,	O
after	O
which	O
the	O
device	O
would	O
go	O
back	O
to	O
interpreting	O
characters	O
normally	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
sequence	O
of	O
,	O
followed	O
by	O
the	O
printable	O
characters	O
,	O
would	O
cause	O
a	O
DEC	O
VT102	O
terminal	O
to	O
move	O
its	O
cursor	B-Application
to	O
the	O
10th	O
cell	O
of	O
the	O
2nd	O
line	O
of	O
the	O
screen	O
.	O
</s>
<s>
The	O
escape	B-Algorithm
character	I-Algorithm
also	O
starts	O
each	O
command	O
sequence	O
in	O
the	O
Hewlett-Packard	B-Language
Printer	I-Language
Command	I-Language
Language	I-Language
.	O
</s>
<s>
An	O
early	O
reference	O
to	O
the	O
term	O
"	O
escape	B-Algorithm
character	I-Algorithm
"	O
is	O
found	O
in	O
Bob	O
Bemer	O
's	O
IBM	O
technical	O
publications	O
,	O
who	O
is	O
credited	O
with	O
inventing	O
this	O
mechanism	O
during	O
his	O
work	O
on	O
the	O
ASCII	B-Protocol
character	I-Protocol
set	I-Protocol
.	O
</s>
<s>
The	O
Escape	B-Device
key	I-Device
is	O
usually	O
found	O
on	O
standard	O
PC	O
keyboards	O
.	O
</s>
<s>
However	O
,	O
it	O
is	O
commonly	O
absent	O
from	O
keyboards	O
for	O
PDAs	O
and	O
other	O
devices	O
not	O
designed	O
primarily	O
for	O
ASCII	B-Protocol
communications	O
.	O
</s>
<s>
The	O
DEC	O
VT220	B-Device
series	O
was	O
one	O
of	O
the	O
few	O
popular	O
keyboards	O
that	O
did	O
not	O
have	O
a	O
dedicated	O
Esc	B-Device
key	I-Device
,	O
instead	O
of	O
using	O
one	O
of	O
the	O
keys	O
above	O
the	O
main	O
keypad	O
.	O
</s>
<s>
In	O
user	B-Application
interfaces	I-Application
of	O
the	O
1970s	O
–	O
1980s	O
it	O
was	O
not	O
uncommon	O
to	O
use	O
this	O
key	O
as	O
an	O
escape	B-Algorithm
character	I-Algorithm
,	O
but	O
in	O
modern	O
desktop	O
computers	O
,	O
such	O
use	O
is	O
dropped	O
.	O
</s>
<s>
Even	O
with	O
no	O
dedicated	O
key	O
,	O
the	O
escape	B-Algorithm
character	I-Algorithm
code	O
could	O
be	O
generated	O
by	O
typing	O
while	O
simultaneously	O
holding	O
down	O
.	O
</s>
<s>
Many	O
modern	O
programming	O
languages	O
specify	O
the	O
double-quote	O
character	O
(	O
)	O
as	O
a	O
delimiter	B-Algorithm
for	O
a	O
string	B-Language
literal	I-Language
.	O
</s>
<s>
The	O
backslash	O
(	O
)	O
escape	B-Algorithm
character	I-Algorithm
typically	O
provides	O
two	O
ways	O
to	O
include	O
double-quotes	O
inside	O
a	O
string	B-Language
literal	I-Language
,	O
either	O
by	O
modifying	O
the	O
meaning	O
of	O
the	O
double-quote	O
character	O
embedded	O
in	O
the	O
string	O
(	O
becomes	O
)	O
,	O
or	O
by	O
modifying	O
the	O
meaning	O
of	O
a	O
sequence	O
of	O
characters	O
including	O
the	O
hexadecimal	O
value	O
of	O
a	O
double-quote	O
character	O
(	O
becomes	O
)	O
.	O
</s>
<s>
C	B-Language
,	O
C++	B-Language
,	O
Java	B-Language
,	O
and	O
Ruby	B-Language
all	O
allow	O
exactly	O
the	O
same	O
two	O
backslash	O
escape	O
styles	O
.	O
</s>
<s>
The	O
PostScript	B-Language
language	I-Language
and	O
Microsoft	O
Rich	O
Text	O
Format	O
also	O
use	O
backslash	O
escapes	O
.	O
</s>
<s>
The	O
quoted-printable	O
encoding	O
uses	O
the	O
equals	O
sign	O
as	O
an	O
escape	B-Algorithm
character	I-Algorithm
.	O
</s>
<s>
URL	O
and	O
URI	B-Protocol
use	O
%	O
-escapes	O
to	O
quote	O
characters	O
with	O
a	O
special	O
meaning	O
,	O
as	O
for	O
non-ASCII	O
characters	O
.	O
</s>
<s>
The	O
ampersand	O
(	O
)	O
character	O
may	O
be	O
considered	O
as	O
an	O
escape	B-Algorithm
character	I-Algorithm
in	O
SGML	B-Language
and	O
derived	O
formats	O
such	O
as	O
HTML	B-Language
and	O
XML	B-Protocol
.	O
</s>
<s>
Some	O
programming	O
languages	O
also	O
provide	O
other	O
ways	O
to	O
represent	O
special	O
characters	O
in	O
literals	O
,	O
without	O
requiring	O
an	O
escape	B-Algorithm
character	I-Algorithm
(	O
see	O
e.g.	O
</s>
<s>
delimiter	B-Algorithm
collision	O
)	O
.	O
</s>
<s>
The	O
Point-to-Point	B-Protocol
Protocol	I-Protocol
(	O
PPP	O
)	O
uses	O
the	O
octet	O
(	O
,	O
or	O
ASCII	B-Protocol
:	O
)	O
as	O
an	O
escape	B-Algorithm
character	I-Algorithm
.	O
</s>
<s>
In	O
Bourne	B-Device
shell	I-Device
(	O
sh	O
)	O
,	O
the	O
asterisk	B-Language
(	O
)	O
and	O
question	O
mark	O
(	O
)	O
characters	O
are	O
wildcard	B-Algorithm
characters	I-Algorithm
expanded	O
via	O
globbing	B-Language
.	O
</s>
<s>
Without	O
a	O
preceding	O
escape	B-Algorithm
character	I-Algorithm
,	O
an	O
will	O
expand	O
to	O
the	O
names	O
of	O
all	O
files	O
in	O
the	O
working	B-Application
directory	I-Application
that	O
do	O
not	O
start	O
with	O
a	O
period	O
if	O
and	O
only	O
if	O
there	O
are	O
such	O
files	O
,	O
otherwise	O
remains	O
unexpanded	O
.	O
</s>
<s>
This	O
modifies	O
the	O
interpretation	O
of	O
the	O
asterisk	B-Language
(	O
)	O
.	O
</s>
<s>
The	O
Windows	B-Device
command-line	I-Device
interpreter	I-Device
uses	O
a	O
caret	O
character	O
(	O
)	O
to	O
escape	O
reserved	O
characters	O
that	O
have	O
special	O
meanings	O
(	O
in	O
particular	O
:	O
,	O
,	O
,	O
,	O
,	O
,	O
)	O
.	O
</s>
<s>
The	O
DOS	B-Operating_System
command-line	I-Operating_System
interpreter	I-Operating_System
,	O
though	O
it	O
has	O
similar	O
syntax	O
,	O
does	O
not	O
support	O
this	O
.	O
</s>
<s>
For	O
example	O
,	O
on	O
the	O
Windows	B-Device
Command	I-Device
Prompt	I-Device
,	O
this	O
will	O
result	O
in	O
a	O
syntax	O
error	O
.	O
</s>
<s>
In	O
Windows	O
,	O
the	O
backslash	O
is	O
used	O
as	O
a	O
path	O
separator	O
;	O
therefore	O
,	O
it	O
generally	O
cannot	O
be	O
used	O
as	O
an	O
escape	B-Algorithm
character	I-Algorithm
.	O
</s>
<s>
PowerShell	B-Application
uses	O
backtick	O
(	O
`	O
)	O
instead	O
.	O
</s>
<s>
Quoted-printable	O
,	O
which	O
encodes	O
8-bit	O
data	O
into	O
7-bit	O
data	O
of	O
limited	O
line	O
lengths	O
,	O
uses	O
the	O
equals	O
sign	O
(	O
)	O
as	O
an	O
escape	B-Algorithm
character	I-Algorithm
.	O
</s>
