<s>
A	O
text	B-Application
editor	I-Application
is	O
a	O
type	O
of	O
computer	B-Application
program	I-Application
that	O
edits	B-Operating_System
plain	O
text	O
.	O
</s>
<s>
Such	O
programs	O
are	O
sometimes	O
known	O
as	O
"	O
notepad	B-Application
"	O
software	O
(	O
e.g.	O
</s>
<s>
Windows	B-Application
Notepad	I-Application
)	O
.	O
</s>
<s>
Text	B-Application
editors	I-Application
are	O
provided	O
with	O
operating	B-General_Concept
systems	I-General_Concept
and	O
software	O
development	O
packages	O
,	O
and	O
can	O
be	O
used	O
to	O
change	O
files	O
such	O
as	O
configuration	B-Protocol
files	I-Protocol
,	O
documentation	O
files	O
and	O
programming	O
language	O
source	O
code	O
.	O
</s>
<s>
There	O
are	O
important	O
differences	O
between	O
plain	O
text	O
(	O
created	O
and	O
edited	O
by	O
text	B-Application
editors	I-Application
)	O
and	O
rich	O
text	O
(	O
such	O
as	O
that	O
created	O
by	O
word	B-General_Concept
processors	I-General_Concept
or	O
desktop	O
publishing	O
software	O
)	O
.	O
</s>
<s>
Each	O
character	O
is	O
represented	O
by	O
a	O
fixed-length	O
sequence	O
of	O
one	O
,	O
two	O
,	O
or	O
four	O
bytes	O
,	O
or	O
as	O
a	O
variable-length	O
sequence	O
of	O
one	O
to	O
four	O
bytes	O
,	O
in	O
accordance	O
to	O
specific	O
character	B-General_Concept
encoding	I-General_Concept
conventions	O
,	O
such	O
as	O
ASCII	B-Protocol
,	O
ISO/IEC	O
2022	O
,	O
Shift	O
JIS	O
,	O
UTF-8	O
,	O
or	O
UTF-16	O
.	O
</s>
<s>
These	O
conventions	O
define	O
many	O
printable	O
characters	O
,	O
but	O
also	O
non-printing	O
characters	O
that	O
control	O
the	B-Language
flow	O
of	O
the	B-Language
text	O
,	O
such	O
as	O
space	O
,	O
line	O
break	O
,	O
and	O
page	O
break	O
.	O
</s>
<s>
Plain	O
text	O
contains	O
no	O
other	O
information	O
about	O
the	B-Language
text	O
itself	O
,	O
not	O
even	O
the	B-Language
character	B-General_Concept
encoding	I-General_Concept
convention	O
employed	O
.	O
</s>
<s>
Plain	O
text	O
is	O
stored	O
in	O
text	B-General_Concept
files	I-General_Concept
,	O
although	O
text	B-General_Concept
files	I-General_Concept
do	O
not	O
exclusively	O
store	O
plain	O
text	O
.	O
</s>
<s>
Since	O
the	B-Language
early	O
days	O
of	O
computers	O
,	O
plain	O
text	O
was	O
(	O
once	O
by	O
necessity	O
and	O
now	O
by	O
convention	O
)	O
generally	O
displayed	O
using	O
a	O
monospace	O
font	O
,	O
such	O
that	O
horizontal	O
alignment	O
and	O
columnar	O
formatting	O
were	O
sometimes	O
done	O
using	O
whitespace	O
characters	O
.	O
</s>
<s>
Rich	O
text	O
,	O
on	O
the	B-Language
other	O
hand	O
,	O
may	O
contain	O
metadata	O
,	O
character	O
formatting	O
data	O
(	O
e.g.	O
</s>
<s>
DOC	B-Operating_System
)	O
,	O
text	B-General_Concept
files	I-General_Concept
adhering	O
to	O
a	O
markup	O
language	O
(	O
e.g.	O
</s>
<s>
RTF	O
or	O
HTML	B-Language
)	O
,	O
or	O
in	O
a	O
hybrid	O
form	O
of	O
both	O
(	O
e.g.	O
</s>
<s>
Office	B-Operating_System
Open	I-Operating_System
XML	I-Operating_System
)	O
.	O
</s>
<s>
Text	B-Application
editors	I-Application
are	O
intended	O
to	O
open	O
and	O
save	O
text	B-General_Concept
files	I-General_Concept
containing	O
either	O
plain	O
text	O
or	O
anything	O
that	O
can	O
be	O
interpreted	O
as	O
plain	O
text	O
,	O
including	O
the	B-Language
markup	O
for	O
rich	O
text	O
or	O
the	B-Language
markup	O
for	O
something	O
else	O
(	O
e.g.	O
</s>
<s>
SVG	B-Application
)	O
.	O
</s>
<s>
Before	O
text	B-Application
editors	I-Application
existed	O
,	O
computer	O
text	O
was	O
punched	O
into	O
cards	B-Architecture
with	O
keypunch	B-Device
machines	I-Device
.	O
</s>
<s>
Physical	O
boxes	O
of	O
these	O
thin	O
cardboard	O
cards	B-Architecture
were	O
then	O
inserted	O
into	O
a	O
card	B-Device
reader	I-Device
.	O
</s>
<s>
Magnetic	O
tape	O
,	O
drum	B-General_Concept
and	O
disk	B-Device
card	B-Device
image	I-Device
files	O
created	O
from	O
such	O
card	B-Architecture
decks	I-Architecture
often	O
had	O
no	O
line-separation	O
characters	O
at	O
all	O
,	O
and	O
assumed	O
fixed-length	O
80	O
-	O
or	O
90-character	O
records	O
.	O
</s>
<s>
An	O
alternative	O
to	O
cards	B-Architecture
was	O
Punched	O
tape	O
.	O
</s>
<s>
It	O
could	O
be	O
created	O
by	O
some	O
teleprinters	O
(	O
such	O
as	O
the	B-Language
Teletype	O
)	O
,	O
which	O
used	O
special	O
characters	O
to	O
indicate	O
ends	O
of	O
records	O
.	O
</s>
<s>
Some	O
early	O
operating	B-General_Concept
systems	I-General_Concept
included	O
batch	O
text	B-Application
editors	I-Application
,	O
either	O
integrated	O
with	O
language	O
processors	O
or	O
as	O
separate	O
utility	O
programs	O
;	O
one	O
early	O
example	O
was	O
the	B-Language
ability	O
to	O
edit	B-Operating_System
SQUOZE	O
source	O
files	O
for	O
SCAT	O
in	O
SHARE	B-Application
Operating	I-Application
System	I-Application
.	O
</s>
<s>
The	B-Language
first	O
interactive	O
text	B-Application
editors	I-Application
were	O
"	B-Application
line	I-Application
editors	I-Application
"	I-Application
oriented	O
to	O
teleprinter	O
-	O
or	O
typewriter-style	O
terminals	O
without	O
displays	O
.	O
</s>
<s>
Commands	O
(	O
often	O
a	O
single	O
keystroke	O
)	O
effected	O
edits	B-Operating_System
to	O
a	O
file	O
at	O
an	O
imaginary	O
insertion	O
point	O
called	O
the	B-Language
"	O
cursor	O
"	O
.	O
</s>
<s>
Edits	B-Operating_System
were	O
verified	O
by	O
typing	O
a	O
command	O
to	O
print	O
a	O
small	O
section	O
of	O
the	B-Language
file	O
,	O
and	O
periodically	O
by	O
printing	O
the	B-Language
entire	O
file	O
.	O
</s>
<s>
In	O
some	O
line	B-Application
editors	I-Application
,	O
the	B-Language
cursor	O
could	O
be	O
moved	O
by	O
commands	O
that	O
specified	O
the	B-Language
line	O
number	O
in	O
the	B-Language
file	O
,	O
text	O
strings	O
(	O
context	O
)	O
for	O
which	O
to	O
search	O
,	O
and	O
eventually	O
regular	B-Language
expressions	I-Language
.	O
</s>
<s>
Line	B-Application
editors	I-Application
were	O
major	O
improvements	O
over	O
keypunching	O
.	O
</s>
<s>
Some	O
line	B-Application
editors	I-Application
could	O
be	O
used	O
by	O
keypunch	B-Device
;	O
editing	O
commands	O
could	O
be	O
taken	O
from	O
a	O
deck	O
of	O
cards	B-Architecture
and	O
applied	O
to	O
a	O
specified	O
file	O
.	O
</s>
<s>
Some	O
common	O
line	B-Application
editors	I-Application
supported	O
a	O
"	O
verify	O
"	O
mode	O
in	O
which	O
change	O
commands	O
displayed	O
the	B-Language
altered	O
lines	O
.	O
</s>
<s>
When	O
computer	B-General_Concept
terminals	I-General_Concept
with	O
video	O
screens	O
became	O
available	O
,	O
screen-based	O
text	B-Application
editors	I-Application
(	O
sometimes	O
called	O
just	O
"	O
screen	O
editors	O
"	O
)	O
became	O
common	O
.	O
</s>
<s>
One	O
of	O
the	B-Language
earliest	O
full-screen	O
editors	O
was	O
O26	B-Application
,	O
which	O
was	O
written	O
for	O
the	B-Language
operator	O
console	O
of	O
the	B-Language
CDC	B-Device
6000	I-Device
series	I-Device
computers	O
in	O
1967	O
.	O
</s>
<s>
Another	O
early	O
full-screen	O
editor	O
was	O
vi	B-Application
.	O
</s>
<s>
Written	O
in	O
the	B-Language
1970s	O
,	O
it	O
is	O
still	O
a	O
standard	O
editor	O
on	O
Unix	B-Application
and	O
Linux	B-Application
operating	I-Application
systems	I-Application
.	O
</s>
<s>
Also	O
written	O
in	O
the	B-Language
1970s	O
was	O
the	B-Language
UCSD	B-Language
Pascal	I-Language
Screen	O
Oriented	O
Editor	O
,	O
which	O
was	O
optimized	O
both	O
for	O
indented	O
source	O
code	O
and	O
general	O
text	O
.	O
</s>
<s>
Emacs	B-Application
,	O
one	O
of	O
the	B-Language
first	O
free	B-Application
and	I-Application
open-source	I-Application
software	I-Application
projects	O
,	O
is	O
another	O
early	O
full-screen	O
or	O
real-time	O
editor	O
,	O
one	O
that	O
was	O
ported	O
to	O
many	O
systems	O
.	O
</s>
<s>
A	O
full-screen	O
editor	O
's	O
ease-of-use	O
and	O
speed	O
(	O
compared	O
to	O
the	B-Language
line-based	O
editors	O
)	O
motivated	O
many	O
early	O
purchases	O
of	O
video	B-General_Concept
terminals	I-General_Concept
.	O
</s>
<s>
The	B-Language
core	O
data	O
structure	O
in	O
a	O
text	B-Application
editor	I-Application
is	O
the	B-Language
one	O
that	O
manages	O
the	B-Language
string	O
(	O
sequence	O
of	O
characters	O
)	O
or	O
list	O
of	O
records	O
that	O
represents	O
the	B-Language
current	O
state	O
of	O
the	B-Language
file	O
being	O
edited	O
.	O
</s>
<s>
While	O
the	B-Language
former	O
could	O
be	O
stored	O
in	O
a	O
single	O
long	O
consecutive	O
array	B-Data_Structure
of	O
characters	O
,	O
</s>
<s>
the	B-Language
desire	O
for	O
text	B-Application
editors	I-Application
that	O
could	O
more	O
quickly	O
insert	O
text	O
,	O
delete	O
text	O
,	O
and	O
undo/redo	O
previous	O
edits	B-Operating_System
led	O
to	O
the	B-Language
development	O
of	O
more	O
complicated	O
sequence	O
data	O
structures	O
.	O
</s>
<s>
A	O
typical	O
text	B-Application
editor	I-Application
uses	O
a	O
gap	B-Data_Structure
buffer	I-Data_Structure
,	O
a	O
linked	B-Data_Structure
list	I-Data_Structure
of	O
lines	O
(	O
as	O
in	O
PaperClip	B-Protocol
)	O
,	O
a	O
piece	B-Data_Structure
table	I-Data_Structure
,	O
or	O
a	O
rope	B-Data_Structure
,	O
as	O
its	O
sequence	O
data	O
structure	O
.	O
</s>
<s>
Some	O
text	B-Application
editors	I-Application
are	O
small	O
and	O
simple	O
,	O
while	O
others	O
offer	O
broad	O
and	O
complex	O
functions	O
.	O
</s>
<s>
For	O
example	O
,	O
Unix	B-Application
and	O
Unix-like	O
operating	B-General_Concept
systems	I-General_Concept
have	O
the	B-Language
pico	B-Operating_System
editor	O
(	O
or	O
a	O
variant	O
)	O
,	O
but	O
many	O
also	O
include	O
the	B-Language
vi	B-Application
and	O
Emacs	B-Application
editors	O
.	O
</s>
<s>
Microsoft	B-Application
Windows	I-Application
systems	O
come	O
with	O
the	B-Language
simple	O
Notepad	B-Application
,	O
though	O
many	O
peopleespecially	O
programmersprefer	O
other	O
editors	O
with	O
more	O
features	O
.	O
</s>
<s>
Under	O
Apple	B-Device
Macintosh	I-Device
's	O
classic	B-Application
Mac	I-Application
OS	I-Application
there	O
was	O
the	B-Language
native	O
TeachText	B-Operating_System
later	O
replaced	O
by	O
SimpleText	B-Operating_System
in	O
1994	O
,	O
which	O
was	O
replaced	O
in	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
by	O
TextEdit	B-Application
,	O
which	O
combines	O
features	O
of	O
a	O
text	B-Application
editor	I-Application
with	O
those	O
typical	O
of	O
a	O
word	B-General_Concept
processor	I-General_Concept
such	O
as	O
rulers	O
,	O
margins	O
and	O
multiple	O
font	O
selection	O
.	O
</s>
<s>
These	O
features	O
are	O
not	O
available	O
simultaneously	O
,	O
but	O
must	O
be	O
switched	O
by	O
user	O
command	O
,	O
or	O
through	O
the	B-Language
program	O
automatically	O
determining	O
the	B-Language
file	O
type	O
.	O
</s>
<s>
Most	O
word	B-General_Concept
processors	I-General_Concept
can	O
read	O
and	O
write	O
files	O
in	O
plain	O
text	O
format	O
,	O
allowing	O
them	O
to	O
open	O
files	O
saved	O
from	O
text	B-Application
editors	I-Application
.	O
</s>
<s>
Saving	O
these	O
files	O
from	O
a	O
word	B-General_Concept
processor	I-General_Concept
,	O
however	O
,	O
requires	O
ensuring	O
the	B-Language
file	O
is	O
written	O
in	O
plain	O
text	O
format	O
,	O
and	O
that	O
any	O
text	B-General_Concept
encoding	I-General_Concept
or	O
BOM	O
settings	O
wo	O
n't	O
obscure	O
the	B-Language
file	O
for	O
its	O
intended	O
use	O
.	O
</s>
<s>
Non-WYSIWYG	O
word	B-General_Concept
processors	I-General_Concept
,	O
such	O
as	O
WordStar	B-Application
,	O
are	O
more	O
easily	O
pressed	O
into	O
service	O
as	O
text	B-Application
editors	I-Application
,	O
and	O
in	O
fact	O
were	O
commonly	O
used	O
as	O
such	O
during	O
the	B-Language
1980s	O
.	O
</s>
<s>
The	B-Language
default	O
file	O
format	O
of	O
these	O
word	B-General_Concept
processors	I-General_Concept
often	O
resembles	O
a	O
markup	O
language	O
,	O
with	O
the	B-Language
basic	O
format	O
being	O
plain	O
text	O
and	O
visual	O
formatting	O
achieved	O
using	O
non-printing	O
control	O
characters	O
or	O
escape	O
sequences	O
.	O
</s>
<s>
Later	O
word	B-General_Concept
processors	I-General_Concept
like	O
Microsoft	B-Application
Word	I-Application
store	O
their	O
files	O
in	O
a	O
binary	O
format	O
and	O
are	O
almost	O
never	O
used	O
to	O
edit	B-Operating_System
plain	O
text	B-General_Concept
files	I-General_Concept
.	O
</s>
<s>
Some	O
text	B-Application
editors	I-Application
can	O
edit	B-General_Concept
unusually	I-General_Concept
large	I-General_Concept
files	I-General_Concept
such	O
as	O
log	B-Application
files	I-Application
or	O
an	O
entire	O
database	O
placed	O
in	O
a	O
single	O
file	O
.	O
</s>
<s>
Simpler	O
text	B-Application
editors	I-Application
may	O
just	O
read	O
files	O
into	O
the	B-Language
computer	O
's	O
main	O
memory	B-Architecture
.	O
</s>
<s>
With	O
larger	O
files	O
,	O
this	O
may	O
be	O
a	O
slow	O
process	O
,	O
and	O
the	B-Language
entire	O
file	O
may	O
not	O
fit	O
.	O
</s>
<s>
Some	O
text	B-Application
editors	I-Application
do	O
not	O
let	O
the	B-Language
user	O
start	O
editing	O
until	O
this	O
read-in	O
is	O
complete	O
.	O
</s>
<s>
Editing	O
performance	O
also	O
often	O
suffers	O
in	O
nonspecialized	O
editors	O
,	O
with	O
the	B-Language
editor	O
taking	O
seconds	O
or	O
even	O
minutes	O
to	O
respond	O
to	O
keystrokes	O
or	O
navigation	O
commands	O
.	O
</s>
<s>
Specialized	O
editors	O
have	O
optimizations	O
such	O
as	O
only	O
storing	O
the	B-Language
visible	O
portion	O
of	O
large	O
files	O
in	O
memory	B-Architecture
,	O
improving	O
editing	O
performance	O
.	O
</s>
<s>
With	O
a	O
programmable	O
editor	O
it	O
is	O
easy	O
to	O
automate	O
repetitive	O
tasks	O
or	O
,	O
add	O
new	O
functionality	O
or	O
even	O
implement	O
a	O
new	O
application	O
within	O
the	B-Language
framework	O
of	O
the	B-Language
editor	O
.	O
</s>
<s>
One	O
common	O
motive	O
for	O
customizing	O
is	O
to	O
make	O
a	O
text	B-Application
editor	I-Application
use	O
the	B-Language
commands	O
of	O
another	O
text	B-Application
editor	I-Application
with	O
which	O
the	B-Language
user	O
is	O
more	O
familiar	O
,	O
or	O
to	O
duplicate	O
missing	O
functionality	O
the	B-Language
user	O
has	O
come	O
to	O
depend	O
on	O
.	O
</s>
<s>
Software	O
developers	O
often	O
use	O
editor	O
customizations	O
tailored	O
to	O
the	B-Language
programming	O
language	O
or	O
development	O
environment	O
they	O
are	O
working	O
in	O
.	O
</s>
<s>
The	B-Language
programmability	O
of	O
some	O
text	B-Application
editors	I-Application
is	O
limited	O
to	O
enhancing	O
the	B-Language
core	O
editing	O
functionality	O
of	O
the	B-Language
program	O
,	O
but	O
Emacs	B-Application
can	O
be	O
extended	O
far	O
beyond	O
editing	O
text	O
filesfor	O
web	O
browsing	O
,	O
reading	O
email	O
,	O
online	B-Protocol
chat	I-Protocol
,	O
managing	O
files	O
or	O
playing	O
games	O
and	O
is	O
often	O
thought	O
of	O
as	O
a	O
Lisp	O
execution	O
environment	O
with	O
a	O
Text	B-Application
User	I-Application
Interface	I-Application
.	O
</s>
<s>
Emacs	B-Application
can	O
even	O
be	O
programmed	O
to	O
emulate	O
Vi	B-Application
,	O
its	O
rival	O
in	O
the	B-Language
traditional	O
editor	B-Language
wars	I-Language
of	O
Unix	B-Operating_System
culture	I-Operating_System
.	O
</s>
<s>
An	O
important	O
group	O
of	O
programmable	O
editors	O
uses	O
REXX	B-Language
as	O
a	O
scripting	B-Language
language	I-Language
.	O
</s>
<s>
Most	O
such	O
editors	O
are	O
derivatives	O
of	O
ISPF/PDF	B-Operating_System
EDIT	B-Operating_System
or	O
of	O
XEDIT	B-Application
,	O
IBM	O
's	O
flagship	O
editor	O
for	O
VM/SP	B-Application
through	O
z/VM	B-Application
.	O
</s>
<s>
Among	O
them	O
are	O
THE	B-Language
,	O
KEDIT	O
,	O
X2	O
,	O
Uni-edit	O
,	O
and	O
SEDIT	O
.	O
</s>
<s>
A	O
text	B-Application
editor	I-Application
written	O
or	O
customized	O
for	O
a	O
specific	O
use	O
can	O
determine	O
what	O
the	B-Language
user	O
is	O
editing	O
and	O
assist	O
the	B-Language
user	O
,	O
often	O
by	O
completing	O
programming	O
terms	O
and	O
showing	O
tooltips	O
with	O
relevant	O
documentation	O
.	O
</s>
<s>
Many	O
text	B-Application
editors	I-Application
for	O
software	O
developers	O
include	O
source	O
code	O
syntax	O
highlighting	O
and	O
automatic	O
indentation	O
to	O
make	O
programs	O
easier	O
to	O
read	O
and	O
write	O
.	O
</s>
<s>
Programming	O
editors	O
often	O
let	O
the	B-Language
user	O
select	O
the	B-Language
name	O
of	O
an	O
include	B-Language
file	I-Language
,	O
function	O
or	O
variable	O
,	O
then	O
jump	O
to	O
its	O
definition	O
.	O
</s>
<s>
Some	O
also	O
allow	O
for	O
easy	O
navigation	O
back	O
to	O
the	B-Language
original	O
section	O
of	O
code	O
by	O
storing	O
the	B-Language
initial	O
cursor	O
location	O
or	O
by	O
displaying	O
the	B-Language
requested	O
definition	O
in	O
a	O
popup	O
window	O
or	O
temporary	O
buffer	O
.	O
</s>
<s>
Some	O
editors	O
implement	O
this	O
ability	O
themselves	O
,	O
but	O
often	O
an	O
auxiliary	O
utility	O
like	O
ctags	B-Device
is	O
used	O
to	O
locate	O
the	B-Language
definitions	O
.	O
</s>
<s>
Find	O
and	O
replace	O
–	O
Text	B-Application
editors	I-Application
provide	O
extensive	O
facilities	O
for	O
searching	O
and	O
replacing	O
strings	O
of	O
text	O
,	O
either	O
individually	O
,	O
or	O
groups	O
of	O
files	O
in	O
opened	O
tabs	O
or	O
a	O
selected	O
folder	O
.	O
</s>
<s>
Advanced	O
editors	O
can	O
use	O
regular	B-Language
expressions	I-Language
to	O
search	O
and	O
edit	B-Operating_System
text	O
or	O
code	O
.	O
</s>
<s>
Cut	B-General_Concept
,	I-General_Concept
copy	I-General_Concept
,	I-General_Concept
and	I-General_Concept
paste	I-General_Concept
–	O
most	O
text	B-Application
editors	I-Application
provide	O
methods	O
to	O
duplicate	O
and	O
move	O
text	O
within	O
the	B-Language
file	O
,	O
or	O
between	O
files	O
.	O
</s>
<s>
Text	O
formatting	O
–	O
Text	B-Application
editors	I-Application
often	O
provide	O
basic	O
visual	O
formatting	O
features	O
like	O
line	B-Algorithm
wrap	I-Algorithm
,	O
auto-indentation	O
,	O
bullet	O
list	O
formatting	O
using	O
ASCII	B-Protocol
characters	I-Protocol
,	O
comment	O
formatting	O
,	O
syntax	O
highlighting	O
and	O
so	O
on	O
.	O
</s>
<s>
These	O
are	O
typically	O
only	O
for	O
display	O
and	O
do	O
not	O
insert	O
formatting	O
codes	O
into	O
the	B-Language
file	O
itself	O
.	O
</s>
<s>
Undo	B-Application
and	I-Application
redo	I-Application
–	O
As	O
with	O
word	B-General_Concept
processors	I-General_Concept
,	O
text	B-Application
editors	I-Application
provide	O
a	O
way	O
to	O
undo	B-Application
and	I-Application
redo	I-Application
the	B-Language
last	O
edit	B-Operating_System
,	O
or	O
more	O
.	O
</s>
<s>
Oftenespecially	O
with	O
older	O
text	O
editorsthere	O
is	O
only	O
one	O
level	O
of	O
edit	B-Operating_System
history	O
remembered	O
and	O
successively	O
issuing	O
the	B-Language
undo	B-Application
command	I-Application
will	O
only	O
"	O
toggle	O
"	O
the	B-Language
last	O
change	O
.	O
</s>
<s>
Modern	O
or	O
more	O
complex	O
editors	O
usually	O
provide	O
a	O
multiple-level	O
history	O
such	O
that	O
issuing	O
the	B-Language
undo	B-Application
command	I-Application
repeatedly	O
will	O
revert	O
the	B-Language
document	O
to	O
successively	O
older	O
edits	B-Operating_System
.	O
</s>
<s>
A	O
separate	O
redo	B-Application
command	O
will	O
cycle	O
the	B-Language
edits	B-Operating_System
"	O
forward	O
"	O
toward	O
the	B-Language
most	O
recent	O
changes	O
.	O
</s>
<s>
The	B-Language
number	O
of	O
changes	O
remembered	O
depends	O
upon	O
the	B-Language
editor	O
and	O
is	O
often	O
configurable	O
by	O
the	B-Language
user	O
.	O
</s>
<s>
Profiles	O
to	O
retain	O
options	O
set	O
by	O
the	B-Language
user	O
between	O
editing	O
session	O
.	O
</s>
<s>
Profile	O
macros	O
with	O
names	O
specified	O
in	O
,	O
e.g.	O
,	O
environment	O
,	O
profile	O
,	O
executed	O
automatically	O
at	O
the	B-Language
beginning	O
of	O
an	O
edit	B-Operating_System
session	O
or	O
when	O
opening	O
a	O
new	O
file	O
.	O
</s>
<s>
Multi-file	O
editing	O
:	O
the	B-Language
ability	O
to	O
edit	B-Operating_System
multiple	O
files	O
during	O
an	O
edit-session	O
,	O
perhaps	O
remembering	O
the	B-Language
current-line	O
cursor	O
of	O
each	O
file	O
,	O
to	O
insert	O
repeated	O
text	O
into	O
each	O
file	O
,	O
copy	O
or	O
move	O
text	O
among	O
files	O
,	O
compare	B-Application
files	I-Application
side-by-side	O
(	O
perhaps	O
with	O
a	O
tiled	O
multiple-document	O
interface	O
)	O
,	O
etc	O
.	O
</s>
<s>
Multi-view	O
editors	O
:	O
the	B-Language
ability	O
to	O
display	O
multiple	O
views	O
of	O
the	B-Language
same	O
file	O
,	O
with	O
independent	O
cursor	O
tracking	O
,	O
synchronizing	O
changes	O
among	O
the	B-Language
windows	O
but	O
providing	O
the	B-Language
same	O
facilities	O
as	O
are	O
available	O
for	O
independent	O
files	O
.	O
</s>
<s>
Collapse/expand	O
,	O
also	O
called	O
folding	B-Application
:	O
the	B-Language
ability	O
to	O
temporarily	O
exclude	O
sections	O
of	O
the	B-Language
text	O
from	O
view	O
.	O
</s>
<s>
This	O
may	O
either	O
be	O
based	O
on	O
a	O
range	O
of	O
line	O
numbers	O
or	O
on	O
some	O
syntactic	O
element	O
,	O
e.g.	O
,	O
excluding	O
everything	O
between	O
a	O
BEGIN	O
;	O
and	O
the	B-Language
matching	O
END	O
;	O
.	O
</s>
<s>
Column-based	O
editing	O
;	O
the	B-Language
ability	O
to	O
alter	O
or	O
insert	O
data	O
at	O
a	O
particular	O
column	O
,	O
or	O
to	O
shift	O
data	O
to	O
specific	O
columns	O
.	O
</s>
<s>
Data	B-General_Concept
transformation	I-General_Concept
–	O
Reading	O
or	O
merging	O
the	B-Language
contents	O
of	O
another	O
text	B-General_Concept
file	I-General_Concept
into	O
the	B-Language
file	O
currently	O
being	O
edited	O
.	O
</s>
<s>
Some	O
text	B-Application
editors	I-Application
provide	O
a	O
way	O
to	O
insert	O
the	B-Language
output	O
of	O
a	O
command	O
issued	O
to	O
the	B-Language
operating	B-General_Concept
system	I-General_Concept
's	O
shell	O
.	O
</s>
<s>
Filtering	B-Application
–	O
Some	O
advanced	O
text	B-Application
editors	I-Application
allow	O
the	B-Language
editor	O
to	O
send	O
all	O
or	O
sections	O
of	O
the	B-Language
file	O
being	O
edited	O
to	O
another	O
utility	O
and	O
read	O
the	B-Language
result	O
back	O
into	O
the	B-Language
file	O
in	O
place	O
of	O
the	B-Language
lines	O
being	O
"	O
filtered	O
"	O
.	O
</s>
<s>
Syntax	O
highlighting	O
–	O
contextually	O
highlights	O
source	O
code	O
,	O
markup	O
languages	O
,	O
config	B-Protocol
files	I-Protocol
and	O
other	O
text	O
that	O
appears	O
in	O
an	O
organized	O
or	O
predictable	O
format	O
.	O
</s>
<s>
Editors	O
generally	O
allow	O
users	O
to	O
customize	O
the	B-Language
colors	O
or	O
styles	O
used	O
for	O
each	O
language	O
element	O
.	O
</s>
<s>
Some	O
text	B-Application
editors	I-Application
also	O
allow	O
users	O
to	O
install	O
and	O
use	O
themes	O
to	O
change	O
the	B-Language
look	B-Application
and	I-Application
feel	I-Application
of	O
the	B-Language
editor	O
's	O
entire	O
user	B-Application
interface	I-Application
.	O
</s>
<s>
Syntax-oriented	O
editors	O
-	O
some	O
editors	O
have	O
support	O
for	O
the	B-Language
syntax	O
of	O
one	O
or	O
more	O
languages	O
,	O
and	O
allow	O
operations	O
in	O
terms	O
of	O
syntactical	O
unit	O
,	O
e.g.	O
,	O
insert	O
a	O
new	O
WHEN	O
clause	O
in	O
a	O
SELECT	O
statement	O
.	O
</s>
<s>
Extensibility	B-Architecture
-	O
a	O
text	B-Application
editor	I-Application
intended	O
for	O
use	O
by	O
programmers	O
must	O
provide	O
some	O
plugin	B-Application
mechanism	O
,	O
or	O
be	O
scriptable	B-Language
,	O
so	O
a	O
programmer	O
can	O
customize	O
the	B-Language
editor	O
with	O
features	O
needed	O
to	O
manage	O
individual	O
software	O
projects	O
,	O
customize	O
functionality	O
or	O
key	O
bindings	O
for	O
specific	O
programming	O
languages	O
or	O
version	B-Architecture
control	I-Architecture
systems	I-Architecture
,	O
or	O
conform	O
to	O
specific	O
coding	B-Language
styles	I-Language
.	O
</s>
<s>
Cursor	O
navigation	O
may	O
vary	O
across	O
text	B-Application
editors	I-Application
.	O
</s>
<s>
For	O
example	O
,	O
pressing	O
End	O
twice	O
may	O
navigate	O
to	O
the	B-Language
end	O
of	O
a	O
wrapped	B-Algorithm
line	I-Algorithm
after	O
one	O
press	O
navigated	O
to	O
the	B-Language
end	O
of	O
an	O
on-screen	O
row	O
of	O
text	O
.	O
</s>
<s>
Command	O
line	O
-	O
some	O
editors	O
,	O
e.g.	O
,	O
ISPF	B-Operating_System
,	O
XEDIT	B-Application
,	O
have	O
a	O
dedicated	O
field	O
on	O
the	B-Language
screen	O
for	O
entering	O
commands	O
as	O
opposed	O
to	O
text	O
.	O
</s>
<s>
Depending	O
on	O
the	B-Language
editor	O
,	O
the	B-Language
user	O
may	O
have	O
to	O
use	O
cursor	O
keys	O
to	O
switch	O
between	O
the	B-Language
command	O
and	O
text	O
fields	O
or	O
the	B-Language
editor	O
may	O
interpret	O
,	O
e.g.	O
,	O
specific	O
function	O
keys	O
,	O
as	O
requests	O
to	O
switch	O
.	O
</s>
<s>
Line	O
commands	O
,	O
also	O
known	O
as	O
prefix	O
commands	O
or	O
sequence	O
commands	O
-	O
Some	O
editors	O
treat	O
a	O
file	O
as	O
an	O
array	B-Data_Structure
of	O
text	O
lines	O
with	O
associated	O
line	O
numbers	O
or	O
sequence	O
numbers	O
,	O
and	O
have	O
a	O
distinct	O
line	O
number	O
field	O
for	O
each	O
text	O
field	O
.	O
</s>
<s>
A	O
line	O
command	O
is	O
a	O
string	O
that	O
the	B-Language
user	O
types	O
into	O
a	O
line	O
number	O
field	O
and	O
that	O
the	B-Language
editor	O
recognizes	O
as	O
a	O
command	O
operating	O
on	O
that	O
specific	O
line	O
or	O
block	O
of	O
lines	O
,	O
e.g.	O
,	O
LC	O
to	O
translate	O
a	O
line	O
to	O
lower	O
case	O
,	O
)	O
)	O
3	O
to	O
shift	O
a	O
block	O
right	O
three	O
columns	O
.	O
</s>
<s>
Despite	O
the	B-Language
name	O
prefix	O
command	O
,	O
some	O
editors	O
allow	O
the	B-Language
sequence	O
field	O
to	O
appear	O
after	O
the	B-Language
text	O
field	O
.	O
</s>
<s>
Source	B-Application
code	I-Application
editors	I-Application
are	O
text	B-Application
editors	I-Application
with	O
additional	O
functionality	O
to	O
facilitate	O
the	B-Language
production	O
of	O
source	O
code	O
.	O
</s>
<s>
These	O
often	O
feature	O
user-programmable	O
syntax	O
highlighting	O
and	O
code	O
navigation	O
functions	O
as	O
well	O
as	O
coding	O
tools	O
or	O
keyboard	O
macros	O
similar	O
to	O
an	O
HTML	B-General_Concept
editor	I-General_Concept
.	O
</s>
<s>
Folding	B-Application
editors	O
.	O
</s>
<s>
This	O
subclass	O
includes	O
so-called	O
"	O
orthodox	O
editors	O
"	O
that	O
are	O
derivatives	O
of	O
Xedit	B-Application
.	O
</s>
<s>
Editors	O
that	O
implement	O
folding	B-Application
without	O
programing-specific	O
features	O
are	O
usually	O
called	O
outliners	B-Application
(	O
see	O
below	O
)	O
.	O
</s>
<s>
IDEs	O
(	O
integrated	B-Application
development	I-Application
environments	I-Application
)	O
are	O
designed	O
to	O
manage	O
and	O
streamline	O
large	O
programming	O
projects	O
.	O
</s>
<s>
They	O
are	O
usually	O
only	O
used	O
for	O
programming	O
as	O
they	O
contain	O
many	O
features	O
unnecessary	O
for	O
simple	B-Operating_System
text	I-Operating_System
editing	O
.	O
</s>
<s>
World	O
Wide	O
Web	O
authors	O
are	O
offered	O
a	O
variety	O
of	O
HTML	B-General_Concept
editors	I-General_Concept
dedicated	O
to	O
the	B-Language
task	O
of	O
creating	O
web	O
pages	O
.	O
</s>
<s>
These	O
include	O
:	O
Dreamweaver	B-Language
,	O
KompoZer	B-General_Concept
and	O
E	O
Text	B-Application
Editor	I-Application
.	O
</s>
<s>
Many	O
offer	O
the	B-Language
option	O
of	O
viewing	O
a	O
work	O
in	O
progress	O
on	O
a	O
built-in	O
HTML	B-Protocol
rendering	I-Protocol
engine	I-Protocol
or	O
standard	O
web	B-Application
browser	I-Application
.	O
</s>
<s>
Most	O
web	O
development	O
is	O
done	O
in	O
a	O
dynamic	B-Language
programming	I-Language
language	I-Language
such	O
as	O
Ruby	B-Language
or	O
PHP	B-Application
using	O
a	O
source	B-Application
code	I-Application
editor	I-Application
or	O
IDE	B-Application
.	O
</s>
<s>
The	B-Language
HTML	B-Language
delivered	O
by	O
all	O
but	O
the	B-Language
simplest	O
static	O
web	O
sites	O
is	O
stored	O
as	O
individual	O
template	B-Language
files	I-Language
that	O
are	O
assembled	O
by	O
the	B-Language
software	O
controlling	O
the	B-Language
site	O
and	O
do	O
not	O
compose	O
a	O
complete	O
HTML	B-Language
document	O
.	O
</s>
<s>
Mathematicians	O
,	O
physicists	O
,	O
and	O
computer	O
scientists	O
often	O
produce	O
articles	O
and	O
books	O
using	O
TeX	B-Application
or	O
LaTeX	B-Application
in	O
plain	O
text	B-General_Concept
files	I-General_Concept
.	O
</s>
<s>
Such	O
documents	O
are	O
often	O
produced	O
by	O
a	O
standard	O
text	B-Application
editor	I-Application
,	O
but	O
some	O
people	O
use	O
specialized	O
TeX	B-Application
editors	O
.	O
</s>
<s>
Outliners	B-Application
.	O
</s>
<s>
Also	O
called	O
tree-based	O
editors	O
,	O
because	O
they	O
combine	O
a	O
hierarchical	O
outline	O
tree	O
with	O
a	O
text	B-Application
editor	I-Application
.	O
</s>
<s>
Folding	B-Application
(	O
see	O
above	O
)	O
can	O
be	O
considered	O
a	O
specialized	O
form	O
of	O
outlining	O
.	O
</s>
<s>
Collaborative	B-Application
editors	I-Application
allow	O
multiple	O
users	O
to	O
work	O
on	O
the	B-Language
same	O
document	O
simultaneously	O
from	O
remote	O
locations	O
over	O
a	O
network	O
.	O
</s>
<s>
The	B-Language
changes	O
made	O
by	O
individual	O
users	O
are	O
tracked	O
and	O
merged	O
into	O
the	B-Language
document	O
automatically	O
to	O
eliminate	O
the	B-Language
possibility	O
of	O
conflicting	O
edits	B-Operating_System
.	O
</s>
<s>
These	O
editors	O
also	O
typically	O
include	O
an	O
online	B-Protocol
chat	I-Protocol
component	O
for	O
discussion	O
among	O
editors	O
.	O
</s>
<s>
Distraction-free	B-Application
editors	I-Application
provide	O
a	O
minimalistic	B-Device
interface	O
with	O
the	B-Language
purpose	O
of	O
isolating	O
the	B-Language
writer	O
from	O
the	B-Language
rest	O
of	O
the	B-Language
applications	O
and	O
operating	B-General_Concept
system	I-General_Concept
,	O
thus	O
being	O
able	O
to	O
focus	O
on	O
the	B-Language
writing	O
without	O
distractions	O
from	O
interface	O
elements	O
like	O
a	O
toolbar	O
or	O
notification	O
area	O
.	O
</s>
<s>
Programmable	O
editors	O
can	O
usually	O
be	O
enhanced	O
to	O
perform	O
any	O
or	O
all	O
of	O
these	O
functions	O
,	O
but	O
simpler	O
editors	O
focus	O
on	O
just	O
one	O
,	O
or	O
,	O
like	O
gPHPedit	B-Language
,	O
are	O
targeted	O
at	O
a	O
single	O
programming	O
language	O
.	O
</s>
