<s>
TeX	B-Application
(	O
,	O
see	O
below	O
)	O
,	O
stylized	O
within	O
the	O
system	O
as	O
,	O
is	O
a	O
typesetting	O
system	O
which	O
was	O
designed	O
and	O
written	O
by	O
computer	O
scientist	O
and	O
Stanford	O
University	O
professor	O
Donald	O
Knuth	O
and	O
first	O
released	O
in	O
1978	O
.	O
</s>
<s>
TeX	B-Application
is	O
a	O
popular	O
means	O
of	O
typesetting	O
complex	O
mathematical	O
formulae	O
;	O
it	O
has	O
been	O
noted	O
as	O
one	O
of	O
the	O
most	O
sophisticated	O
digital	O
typographical	O
systems	O
.	O
</s>
<s>
TeX	B-Application
is	O
widely	O
used	O
in	O
academia	O
,	O
especially	O
in	O
mathematics	O
,	O
computer	B-General_Concept
science	I-General_Concept
,	O
economics	O
,	O
political	O
science	O
,	O
engineering	O
,	O
linguistics	O
,	O
physics	O
,	O
statistics	O
,	O
and	O
quantitative	O
psychology	O
.	O
</s>
<s>
It	O
has	O
long	O
since	O
displaced	O
Unix	B-Language
troff	I-Language
,	O
the	O
previously	O
favored	O
formatting	O
system	O
,	O
in	O
most	O
Unix	B-Application
installations	O
.	O
</s>
<s>
It	O
is	O
also	O
used	O
for	O
many	O
other	O
typesetting	O
tasks	O
,	O
especially	O
in	O
the	O
form	O
of	O
LaTeX	B-Application
,	O
ConTeXt	O
,	O
and	O
other	O
macro	O
packages	O
.	O
</s>
<s>
TeX	B-Application
was	O
designed	O
with	O
two	O
main	O
goals	O
in	O
mind	O
:	O
to	O
allow	O
anybody	O
to	O
produce	O
high-quality	O
books	O
with	O
minimal	O
effort	O
,	O
and	O
to	O
provide	O
a	O
system	O
that	O
would	O
give	O
exactly	O
the	O
same	O
results	O
on	O
all	O
computers	O
,	O
at	O
any	O
point	O
in	O
time	O
(	O
together	O
with	O
the	O
Metafont	B-Operating_System
language	O
for	O
font	O
description	O
and	O
the	O
Computer	O
Modern	O
family	O
of	O
typefaces	O
)	O
.	O
</s>
<s>
TeX	B-Application
is	O
free	B-Application
software	I-Application
,	O
which	O
made	O
it	O
accessible	O
to	O
a	O
wide	O
range	O
of	O
users	O
.	O
</s>
<s>
When	O
the	O
first	O
paper	O
volume	O
of	O
Knuth	O
's	O
The	B-General_Concept
Art	I-General_Concept
of	I-General_Concept
Computer	I-General_Concept
Programming	I-General_Concept
was	O
published	O
in	O
1968	O
,	O
it	O
was	O
typeset	O
using	O
hot	O
metal	O
typesetting	O
on	O
a	O
Monotype	O
machine	O
.	O
</s>
<s>
On	O
13	O
May	O
1977	O
,	O
he	O
wrote	O
a	O
memo	O
to	O
himself	O
describing	O
the	O
basic	O
features	O
of	O
TeX	B-Application
.	O
</s>
<s>
Guy	O
Steele	O
happened	O
to	O
be	O
at	O
Stanford	O
during	O
the	O
summer	O
of	O
1978	O
,	O
when	O
Knuth	O
was	O
developing	O
his	O
first	O
version	O
of	O
TeX	B-Application
.	O
</s>
<s>
When	O
Steele	O
returned	O
to	O
the	O
Massachusetts	O
Institute	O
of	O
Technology	O
that	O
autumn	O
,	O
he	O
rewrote	O
TeX	B-Application
's	O
input/output	B-General_Concept
(	O
I/O	B-General_Concept
)	O
to	O
run	O
under	O
the	O
Incompatible	B-Application
Timesharing	I-Application
System	I-Application
(	O
ITS	O
)	O
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
The	O
first	O
version	O
of	O
TeX	B-Application
,	O
called	O
TeX78	O
,	O
was	O
written	O
in	O
the	O
SAIL	B-Language
programming	I-Language
language	I-Language
to	O
run	O
on	O
a	O
PDP-10	B-Device
under	O
Stanford	O
's	O
WAITS	B-Application
operating	B-General_Concept
system	I-General_Concept
.	O
</s>
<s>
For	O
later	O
versions	O
of	O
TeX	B-Application
,	O
Knuth	O
invented	O
the	O
concept	O
of	O
literate	B-Application
programming	I-Application
,	O
a	O
way	O
of	O
producing	O
compilable	O
source	O
code	O
and	O
cross-linked	O
documentation	O
typeset	O
in	O
TeX	B-Application
from	O
the	O
same	O
original	O
file	O
.	O
</s>
<s>
The	O
language	O
used	O
is	O
called	O
WEB	O
and	O
produces	O
programs	O
in	O
DEC	B-Device
PDP-10	I-Device
Pascal	B-Application
.	O
</s>
<s>
TeX82	O
,	O
a	O
new	O
version	O
of	O
TeX	B-Application
rewritten	O
from	O
scratch	O
,	O
was	O
published	O
in	O
1982	O
.	O
</s>
<s>
Among	O
other	O
changes	O
,	O
the	O
original	O
hyphenation	B-Algorithm
algorithm	I-Algorithm
was	O
replaced	O
by	O
a	O
new	O
algorithm	O
written	O
by	O
Frank	O
Liang	O
.	O
</s>
<s>
TeX82	O
also	O
uses	O
fixed-point	O
arithmetic	O
instead	O
of	O
floating-point	B-Algorithm
,	O
to	O
ensure	O
reproducibility	O
of	O
the	O
results	O
across	O
different	O
computer	O
hardware	O
,	O
and	O
includes	O
a	O
real	O
,	O
Turing-complete	B-Algorithm
programming	O
language	O
,	O
following	O
intense	O
lobbying	O
by	O
Guy	O
Steele	O
.	O
</s>
<s>
In	O
1989	O
,	O
Donald	O
Knuth	O
released	O
new	O
versions	O
of	O
TeX	B-Application
and	O
Metafont	B-Operating_System
.	O
</s>
<s>
Despite	O
his	O
desire	O
to	O
keep	O
the	O
program	O
stable	O
,	O
Knuth	O
realised	O
that	O
128different	O
characters	O
for	O
the	O
text	O
input	O
were	O
not	O
enough	O
to	O
accommodate	O
foreign	O
languages	O
;	O
the	O
main	O
change	O
in	O
version	O
3.0	O
of	O
TeX	B-Application
(	O
also	O
called	O
TeX90	O
)	O
is	O
thus	O
the	O
ability	O
to	O
work	O
with	O
8-bit	O
inputs	O
,	O
allowing	O
256	O
different	O
characters	O
in	O
the	O
text	O
input	O
.	O
</s>
<s>
Since	O
version	O
3	O
,	O
TeX	B-Application
has	O
used	O
an	O
idiosyncratic	O
version	O
numbering	O
system	O
,	O
where	O
updates	O
have	O
been	O
indicated	O
by	O
adding	O
an	O
extra	O
digit	O
at	O
the	O
end	O
of	O
the	O
decimal	O
,	O
so	O
that	O
the	O
version	O
number	O
asymptotically	O
approaches	O
.	O
</s>
<s>
This	O
is	O
a	O
reflection	O
of	O
the	O
fact	O
that	O
TeX	B-Application
is	O
now	O
very	O
stable	O
,	O
and	O
only	O
minor	O
updates	O
are	O
anticipated	O
.	O
</s>
<s>
The	O
current	O
version	O
of	O
TeX	B-Application
is	O
3.141592653	O
;	O
it	O
was	O
last	O
updated	O
in	O
2021	O
.	O
</s>
<s>
The	O
design	O
was	O
frozen	O
after	O
version	O
3.0	O
,	O
and	O
no	O
new	O
feature	O
or	O
fundamental	O
change	O
will	O
be	O
added	O
,	O
so	O
all	O
newer	O
versions	O
will	O
contain	O
only	O
bug	B-Error_Name
fixes	O
.	O
</s>
<s>
Even	O
though	O
Donald	O
Knuth	O
himself	O
has	O
suggested	O
a	O
few	O
areas	O
in	O
which	O
TeX	B-Application
could	O
have	O
been	O
improved	O
,	O
he	O
indicated	O
that	O
he	O
firmly	O
believes	O
that	O
having	O
an	O
unchanged	O
system	O
that	O
will	O
produce	O
the	O
same	O
output	O
now	O
and	O
in	O
the	O
future	O
is	O
more	O
important	O
than	O
introducing	O
new	O
features	O
.	O
</s>
<s>
For	O
this	O
reason	O
,	O
he	O
has	O
stated	O
that	O
the	O
"	O
absolutely	O
final	O
change	O
(	O
to	O
be	O
made	O
after	O
my	O
death	O
)	O
"	O
will	O
be	O
to	O
change	O
the	O
version	O
number	O
to	O
,	O
at	O
which	O
point	O
all	O
remaining	O
bugs	B-Error_Name
will	O
become	O
features	O
.	O
</s>
<s>
Likewise	O
,	O
versions	O
of	O
Metafont	B-Operating_System
after	O
2.0	O
asymptotically	O
approach	O
(	O
currently	O
at	O
2.7182818	O
)	O
,	O
and	O
a	O
similar	O
change	O
will	O
be	O
applied	O
after	O
Knuth	O
's	O
death	O
.	O
</s>
<s>
Since	O
the	O
source	O
code	O
of	O
TeX	B-Application
is	O
essentially	O
in	O
the	O
public	O
domain	O
(	O
see	O
below	O
)	O
,	O
other	O
programmers	O
are	O
allowed	O
(	O
and	O
explicitly	O
encouraged	O
)	O
to	O
improve	O
the	O
system	O
,	O
but	O
are	O
required	O
to	O
use	O
another	O
name	O
to	O
distribute	O
the	O
modified	O
TeX	B-Application
,	O
meaning	O
that	O
the	O
source	O
code	O
can	O
still	O
evolve	O
.	O
</s>
<s>
For	O
example	O
,	O
the	O
Omega	B-General_Concept
project	O
was	O
developed	O
after	O
1991	O
,	O
primarily	O
to	O
enhance	O
TeX	B-Application
's	O
multilingual	O
typesetting	O
abilities	O
.	O
</s>
<s>
Knuth	O
created	O
"	O
unofficial	O
"	O
modified	O
versions	O
,	O
such	O
as	O
TeX-XeT	O
,	O
which	O
allows	O
a	O
user	O
to	O
mix	O
texts	O
written	O
in	O
left-to-right	O
and	O
right-to-left	O
writing	O
systems	O
in	O
the	O
same	O
document	O
.	O
</s>
<s>
In	O
several	O
technical	O
fields	O
such	O
as	O
computer	B-General_Concept
science	I-General_Concept
,	O
mathematics	O
,	O
engineering	O
and	O
physics	O
,	O
TeX	B-Application
has	O
become	O
a	O
de	O
facto	O
standard	O
.	O
</s>
<s>
Many	O
thousands	O
of	O
books	O
have	O
been	O
published	O
using	O
TeX	B-Application
,	O
including	O
books	O
published	O
by	O
Addison-Wesley	O
,	O
Cambridge	O
University	O
Press	O
,	O
Elsevier	O
,	O
Oxford	O
University	O
Press	O
,	O
and	O
Springer	O
.	O
</s>
<s>
Numerous	O
journals	O
in	O
these	O
fields	O
are	O
produced	O
using	O
TeX	B-Application
or	O
LaTeX	B-Application
,	O
allowing	O
authors	O
to	O
submit	O
their	O
raw	O
manuscript	O
written	O
in	O
TeX	B-Application
.	O
</s>
<s>
While	O
many	O
publications	O
in	O
other	O
fields	O
,	O
including	O
dictionaries	O
and	O
legal	O
publications	O
,	O
have	O
been	O
produced	O
using	O
TeX	B-Application
,	O
it	O
has	O
not	O
been	O
as	O
successful	O
as	O
in	O
the	O
more	O
technical	O
fields	O
,	O
as	O
TeX	B-Application
was	O
primarily	O
designed	O
to	O
typeset	O
mathematics	O
.	O
</s>
<s>
When	O
he	O
designed	O
TeX	B-Application
,	O
Donald	O
Knuth	O
did	O
not	O
believe	O
that	O
a	O
single	O
typesetting	O
system	O
would	O
fit	O
everyone	O
's	O
needs	O
;	O
instead	O
,	O
he	O
designed	O
many	O
hooks	O
inside	O
the	O
program	O
so	O
that	O
it	O
would	O
be	O
possible	O
to	O
write	O
extensions	O
,	O
and	O
released	O
the	O
source	O
code	O
,	O
hoping	O
that	O
the	O
publishers	O
would	O
design	O
versions	O
tailoring	O
to	O
their	O
own	O
needs	O
.	O
</s>
<s>
While	O
such	O
extensions	O
have	O
been	O
created	O
(	O
including	O
some	O
by	O
Knuth	O
himself	O
)	O
,	O
most	O
people	O
have	O
extended	O
TeX	B-Application
only	O
using	O
macros	O
and	O
it	O
has	O
remained	O
a	O
system	O
associated	O
with	O
technical	O
typesetting	O
.	O
</s>
<s>
TeX	B-Application
commands	O
commonly	O
start	O
with	O
a	O
backslash	O
and	O
are	O
grouped	O
with	O
curly	O
braces	O
.	O
</s>
<s>
Almost	O
all	O
of	O
TeX	B-Application
's	O
syntactic	O
properties	O
can	O
be	O
changed	O
on	O
the	O
fly	O
,	O
which	O
makes	O
TeX	B-Application
input	O
hard	O
to	O
parse	O
by	O
anything	O
but	O
TeX	B-Application
itself	O
.	O
</s>
<s>
TeX	B-Application
is	O
a	O
macro	O
-	O
and	O
token-based	O
language	O
:	O
many	O
commands	O
,	O
including	O
most	O
user-defined	O
ones	O
,	O
are	O
expanded	O
on	O
the	O
fly	O
until	O
only	O
unexpandable	O
tokens	O
remain	O
,	O
which	O
are	O
then	O
executed	O
.	O
</s>
<s>
Tail	B-Language
recursion	I-Language
of	O
macros	O
takes	O
no	O
memory	O
,	O
and	O
if-then-else	O
constructs	O
are	O
available	O
.	O
</s>
<s>
This	O
makes	O
TeX	B-Application
a	O
Turing-complete	B-Algorithm
language	O
even	O
at	O
the	O
expansion	O
level	O
.	O
</s>
<s>
Here	O
,	O
the	O
characters	O
get	O
assembled	O
into	O
a	O
paragraph	O
,	O
and	O
TeX	B-Application
's	O
paragraph	O
breaking	O
algorithm	O
works	O
by	O
optimizing	O
breakpoints	O
over	O
the	O
whole	O
paragraph	O
.	O
</s>
<s>
The	O
TeX	B-Application
system	O
has	O
precise	O
knowledge	O
of	O
the	O
sizes	O
of	O
all	O
characters	O
and	O
symbols	O
,	O
and	O
using	O
this	O
information	O
,	O
it	O
computes	O
the	O
optimal	O
arrangement	O
of	O
letters	O
per	O
line	O
and	O
lines	O
per	O
page	O
.	O
</s>
<s>
It	O
then	O
produces	O
a	O
DVI	B-Application
file	O
(	O
"	O
DeVice	B-Operating_System
Independent	I-Operating_System
"	O
)	O
containing	O
the	O
final	O
locations	O
of	O
all	O
characters	O
.	O
</s>
<s>
This	O
DVI	B-Application
file	O
can	O
then	O
be	O
printed	O
directly	O
given	O
an	O
appropriate	O
printer	O
driver	O
,	O
or	O
it	O
can	O
be	O
converted	O
to	O
other	O
formats	O
.	O
</s>
<s>
Nowadays	O
,	O
pdfTeX	B-Language
is	O
often	O
used	O
,	O
which	O
bypasses	O
DVI	B-Application
generation	O
altogether	O
.	O
</s>
<s>
The	O
base	O
TeX	B-Application
system	O
understands	O
about	O
300	O
commands	O
,	O
called	O
primitives	O
.	O
</s>
<s>
These	O
low-level	O
commands	O
are	O
rarely	O
used	O
directly	O
by	O
users	O
,	O
and	O
most	O
functionality	O
is	O
provided	O
by	O
format	O
files	O
(	O
predumped	O
memory	O
images	O
of	O
TeX	B-Application
after	O
large	O
macro	O
collections	O
have	O
been	O
loaded	O
)	O
.	O
</s>
<s>
Knuth	O
's	O
original	O
default	O
format	O
,	O
which	O
adds	O
about	O
600	O
commands	O
,	O
is	O
Plain	B-Application
TeX	I-Application
.	O
</s>
<s>
The	O
most	O
widely	O
used	O
format	O
is	O
LaTeX	B-Application
,	O
originally	O
developed	O
by	O
Leslie	O
Lamport	O
,	O
which	O
incorporates	O
document	O
styles	O
for	O
books	O
,	O
letters	O
,	O
slides	O
,	O
etc.	O
,	O
and	O
adds	O
support	O
for	O
referencing	O
and	O
automatic	O
numbering	O
of	O
sections	O
and	O
equations	O
.	O
</s>
<s>
Another	O
widely	O
used	O
format	O
,	O
AMS-TeX	B-General_Concept
,	O
is	O
produced	O
by	O
the	O
American	O
Mathematical	O
Society	O
and	O
provides	O
many	O
more	O
user-friendly	O
commands	O
,	O
which	O
can	O
be	O
altered	O
by	O
journals	O
to	O
fit	O
with	O
their	O
house	O
style	O
.	O
</s>
<s>
Most	O
of	O
the	O
features	O
of	O
AMS-TeX	B-General_Concept
can	O
be	O
used	O
in	O
LaTeX	B-Application
by	O
using	O
the	O
"	O
AMS	O
packages	O
"	O
(	O
e.g.	O
,	O
amsmath	B-General_Concept
,	O
amssymb	O
)	O
and	O
the	O
"	O
AMS	O
document	O
classes	O
"	O
(	O
e.g.	O
,	O
amsart	O
,	O
amsbook	O
)	O
.	O
</s>
<s>
This	O
is	O
then	O
referred	O
to	O
as	O
AMS-LaTeX	B-General_Concept
.	O
</s>
<s>
A	O
sample	O
Hello	O
world	O
program	O
in	O
plain	B-Application
TeX	I-Application
is	O
:	O
</s>
<s>
This	O
might	O
be	O
in	O
a	O
file	O
myfile.tex	O
,	O
as	O
.tex	B-Application
is	O
a	O
common	O
file	O
extension	O
for	O
plain	B-Application
TeX	I-Application
files	O
.	O
</s>
<s>
By	O
default	O
,	O
everything	O
that	O
follows	O
a	O
percent	O
sign	O
on	O
a	O
line	O
is	O
a	O
comment	O
,	O
ignored	O
by	O
TeX	B-Application
.	O
</s>
<s>
Running	O
TeX	B-Application
on	O
this	O
file	O
(	O
for	O
example	O
,	O
by	O
typing	O
tex	B-Application
myfile.tex	O
in	O
a	O
command-line	B-Application
interpreter	O
,	O
or	O
by	O
calling	O
it	O
from	O
a	O
graphical	B-Application
user	I-Application
interface	I-Application
)	O
will	O
create	O
an	O
output	O
file	O
called	O
myfile.dvi	O
,	O
representing	O
the	O
content	O
of	O
the	O
page	O
in	O
a	O
device	B-Operating_System
independent	I-Operating_System
format	O
(	O
DVI	B-Application
)	O
.	O
</s>
<s>
A	O
DVI	B-Application
file	O
could	O
then	O
be	O
either	O
viewed	O
on	O
screen	O
or	O
converted	O
to	O
a	O
suitable	O
format	O
for	O
any	O
of	O
the	O
various	O
printers	O
for	O
which	O
a	O
device	O
driver	O
existed	O
(	O
printer	O
support	O
was	O
generally	O
not	O
an	O
operating	B-General_Concept
system	I-General_Concept
feature	O
at	O
the	O
time	O
that	O
TeX	B-Application
was	O
created	O
)	O
.	O
</s>
<s>
Knuth	O
has	O
said	O
that	O
there	O
is	O
nothing	O
inherent	O
in	O
TeX	B-Application
that	O
requires	O
DVI	B-Application
as	O
the	O
output	O
format	O
,	O
and	O
later	O
versions	O
of	O
TeX	B-Application
,	O
notably	O
pdfTeX	B-Language
,	O
XeTeX	B-Application
and	O
LuaTeX	B-Language
,	O
all	O
support	O
output	O
directly	O
to	O
PDF	B-Application
.	O
</s>
<s>
TeX	B-Application
provides	O
a	O
different	O
text	O
syntax	O
specifically	O
for	O
mathematical	O
formulas	O
.	O
</s>
<s>
In	O
a	O
document	O
,	O
entering	O
mathematics	O
mode	O
is	O
done	O
by	O
starting	O
with	O
a	O
$	O
symbol	O
,	O
then	O
entering	O
a	O
formula	O
in	O
TeX	B-Application
syntax	O
,	O
and	O
closing	O
again	O
with	O
another	O
of	O
the	O
same	O
symbol	O
.	O
</s>
<s>
Knuth	O
explained	O
in	O
jest	O
that	O
he	O
chose	O
the	O
dollar	O
sign	O
to	O
indicate	O
the	O
beginning	O
and	O
end	O
of	O
mathematical	O
mode	O
in	O
plain	B-Application
TeX	I-Application
because	O
typesetting	O
mathematics	O
was	O
traditionally	O
supposed	O
to	O
be	O
expensive	O
.	O
</s>
<s>
(	O
The	O
examples	O
here	O
are	O
not	O
actually	O
rendered	O
with	O
TeX	B-Application
;	O
spacing	O
,	O
character	O
sizes	O
,	O
and	O
all	O
else	O
may	O
differ	O
.	O
)	O
</s>
<s>
The	O
TeX	B-Application
software	O
incorporates	O
several	O
aspects	O
that	O
were	O
not	O
available	O
,	O
or	O
were	O
of	O
lower	O
quality	O
,	O
in	O
other	O
typesetting	O
programs	O
at	O
the	O
time	O
when	O
TeX	B-Application
was	O
released	O
.	O
</s>
<s>
Since	O
the	O
primary	O
goal	O
of	O
the	O
TeX	B-Application
language	O
is	O
high-quality	O
typesetting	O
for	O
publishers	O
of	O
books	O
,	O
Knuth	O
gave	O
a	O
lot	O
of	O
attention	O
to	O
the	O
spacing	O
rules	O
for	O
mathematical	O
formulae	O
.	O
</s>
<s>
He	O
took	O
three	O
bodies	O
of	O
work	O
that	O
he	O
considered	O
to	O
be	O
standards	O
of	O
excellence	O
for	O
mathematical	O
typography	O
:	O
the	O
books	O
typeset	O
by	O
the	O
Addison-Wesley	O
Publishing	O
house	O
(	O
the	O
publisher	O
of	O
The	B-General_Concept
Art	I-General_Concept
of	I-General_Concept
Computer	I-General_Concept
Programming	I-General_Concept
)	O
under	O
the	O
supervision	O
of	O
Hans	O
Wolf	O
;	O
editions	O
of	O
the	O
mathematical	O
journal	O
Acta	O
Mathematica	O
dating	O
from	O
around	O
1910	O
;	O
and	O
a	O
copy	O
of	O
Indagationes	O
Mathematicae	O
,	O
a	O
Dutch	O
mathematics	O
journal	O
.	O
</s>
<s>
While	O
TeX	B-Application
provides	O
some	O
basic	O
rules	O
and	O
the	O
tools	O
needed	O
to	O
specify	O
proper	O
spacing	O
,	O
the	O
exact	O
parameters	O
depend	O
on	O
the	O
font	O
used	O
to	O
typeset	O
the	O
formula	O
.	O
</s>
<s>
The	O
typesetting	O
of	O
math	O
in	O
TeX	B-Application
is	O
not	O
without	O
criticism	O
,	O
particularly	O
with	O
respect	O
to	O
technical	O
details	O
of	O
the	O
font	O
metrics	O
,	O
which	O
were	O
designed	O
in	O
an	O
era	O
when	O
significant	O
attention	O
was	O
paid	O
to	O
storage	O
requirements	O
.	O
</s>
<s>
The	O
OpenType	O
math	O
font	O
specification	O
largely	O
borrows	O
from	O
TeX	B-Application
,	O
but	O
has	O
some	O
new	O
features/enhancements	O
.	O
</s>
<s>
In	O
comparison	O
with	O
manual	O
typesetting	O
,	O
the	O
problem	O
of	O
justification	O
is	O
easy	O
to	O
solve	O
with	O
a	O
digital	O
system	O
such	O
as	O
TeX	B-Application
,	O
which	O
,	O
provided	O
that	O
good	O
points	O
for	O
line	O
breaking	O
have	O
been	O
defined	O
,	O
can	O
automatically	O
spread	O
the	O
spaces	O
between	O
words	O
to	O
fill	O
in	O
the	O
line	O
.	O
</s>
<s>
In	O
comparison	O
,	O
the	O
total-fit	O
line-breaking	O
algorithm	O
used	O
by	O
TeX	B-Application
and	O
developed	O
by	O
Donald	O
Knuth	O
and	O
Michael	O
Plass	O
considers	O
all	O
the	O
possible	O
breakpoints	O
in	O
a	O
paragraph	O
,	O
and	O
finds	O
the	O
combination	O
of	O
line	O
breaks	O
that	O
will	O
produce	O
the	O
most	O
globally	O
pleasing	O
arrangement	O
.	O
</s>
<s>
However	O
,	O
by	O
using	O
the	O
method	O
of	O
dynamic	B-Algorithm
programming	I-Algorithm
,	O
the	O
complexity	O
of	O
the	O
algorithm	O
can	O
be	O
brought	O
down	O
to	O
(	O
see	O
Big	O
O	O
notation	O
)	O
.	O
</s>
<s>
TeX	B-Application
's	O
line-breaking	O
algorithm	O
has	O
been	O
adopted	O
by	O
several	O
other	O
programs	O
,	O
such	O
as	O
Adobe	B-Operating_System
InDesign	I-Operating_System
(	O
a	O
desktop	O
publishing	O
application	B-Application
)	O
and	O
the	O
GNU	B-Operating_System
fmt	B-Application
Unix	B-Application
command	B-Application
line	I-Application
utility	O
.	O
</s>
<s>
The	O
original	O
version	O
of	O
TeX	B-Application
used	O
a	O
hyphenation	B-Algorithm
algorithm	I-Algorithm
based	O
on	O
a	O
set	O
of	O
rules	O
for	O
the	O
removal	O
of	O
prefixes	O
and	O
suffixes	O
of	O
words	O
,	O
and	O
for	O
deciding	O
if	O
it	O
should	O
insert	O
a	O
break	O
between	O
the	O
two	O
consonants	O
in	O
a	O
pattern	O
of	O
the	O
form	O
vowel	O
–	O
consonant	O
–	O
consonant	O
–	O
vowel	O
(	O
which	O
is	O
possible	O
most	O
of	O
the	O
time	O
)	O
.	O
</s>
<s>
TeX82	O
introduced	O
a	O
new	O
hyphenation	B-Algorithm
algorithm	I-Algorithm
,	O
designed	O
by	O
Frank	O
Liang	O
in	O
1983	O
,	O
to	O
assign	O
priorities	O
to	O
breakpoints	O
in	O
letter	O
groups	O
.	O
</s>
<s>
If	O
TeX	B-Application
must	O
find	O
the	O
acceptable	O
hyphenation	O
positions	O
in	O
the	O
word	O
encyclopedia	O
,	O
for	O
example	O
,	O
it	O
will	O
consider	O
all	O
the	O
subwords	O
of	O
the	O
extended	O
word	O
.encyclopedia.	O
,	O
where	O
.	O
</s>
<s>
The	O
list	O
of	O
subwords	O
includes	O
all	O
the	O
subwords	O
of	O
length	O
1	O
(	O
.	O
,	O
e	O
,	O
n	O
,	O
c	B-Language
,	O
y	O
,	O
etc	O
.	O
</s>
<s>
TeX	B-Application
will	O
then	O
look	O
into	O
its	O
list	O
of	O
hyphenation	O
patterns	O
,	O
and	O
find	O
subwords	O
for	O
which	O
it	O
has	O
calculated	O
the	O
desirability	O
of	O
hyphenation	O
at	O
each	O
position	O
.	O
</s>
<s>
For	O
each	O
position	O
in	O
the	O
word	O
,	O
TeX	B-Application
will	O
calculate	O
the	O
maximum	O
value	O
obtained	O
among	O
all	O
matching	O
patterns	O
,	O
yielding	O
en1cy1c4l4o3p4e5d4i3a4	O
.	O
</s>
<s>
In	O
addition	O
,	O
a	O
list	O
of	O
exceptions	O
(	O
words	O
for	O
which	O
the	O
patterns	O
do	O
not	O
predict	O
the	O
correct	O
hyphenation	O
)	O
are	O
included	O
with	O
the	O
Plain	B-Application
TeX	I-Application
format	O
;	O
additional	O
ones	O
can	O
be	O
specified	O
by	O
the	O
user	O
.	O
</s>
<s>
Metafont	B-Operating_System
,	O
not	O
strictly	O
part	O
of	O
TeX	B-Application
,	O
is	O
a	O
font	O
description	O
system	O
which	O
allows	O
the	O
designer	O
to	O
describe	O
characters	O
algorithmically	O
.	O
</s>
<s>
It	O
uses	O
Bézier	O
curves	O
in	O
a	O
fairly	O
standard	O
way	O
to	O
generate	O
the	O
actual	O
characters	O
to	O
be	O
displayed	O
,	O
but	O
Knuth	O
devotes	O
substantial	O
attention	O
to	O
the	O
rasterizing	O
problem	O
on	O
bitmapped	B-Algorithm
displays	O
.	O
</s>
<s>
This	O
term	O
derives	O
from	O
the	O
fact	O
that	O
Metafont	B-Operating_System
describes	O
characters	O
as	O
having	O
been	O
drawn	O
by	O
abstract	O
brushes	O
(	O
and	O
erasers	O
)	O
.	O
</s>
<s>
It	O
is	O
commonly	O
believed	O
that	O
TeX	B-Application
is	O
based	O
on	O
bitmap	O
fonts	O
but	O
,	O
in	O
fact	O
,	O
these	O
programs	O
"	O
know	O
"	O
nothing	O
about	O
the	O
fonts	O
that	O
they	O
are	O
using	O
other	O
than	O
their	O
dimensions	O
.	O
</s>
<s>
Computer	O
Modern	O
(	O
commonly	O
known	O
as	O
"	O
the	O
TeX	B-Application
font	O
"	O
)	O
is	O
freely	O
available	O
in	O
Type	O
1	O
format	O
,	O
as	O
are	O
the	O
AMS	O
math	O
fonts	O
.	O
</s>
<s>
Users	O
of	O
TeX	B-Application
systems	O
that	O
output	O
directly	O
to	O
PDF	B-Application
,	O
such	O
as	O
pdfTeX	B-Language
,	O
XeTeX	B-Application
,	O
or	O
LuaTeX	B-Language
,	O
generally	O
never	O
use	O
Metafont	B-Operating_System
output	O
at	O
all	O
.	O
</s>
<s>
TeX	B-Application
documents	O
are	O
written	O
and	O
programmed	O
using	O
an	O
unusual	O
macro	O
language	O
.	O
</s>
<s>
It	O
differs	O
with	O
most	O
widely	O
used	O
lexical	O
preprocessors	O
like	O
M4	B-Device
,	O
in	O
that	O
the	O
body	O
of	O
a	O
macro	O
gets	O
tokenized	O
at	O
definition	O
time	O
.	O
</s>
<s>
The	O
TeX	B-Application
macro	I-Application
language	O
has	O
been	O
used	O
to	O
write	O
larger	O
document	O
production	O
systems	O
,	O
most	O
notably	O
including	O
LaTeX	B-Application
and	O
ConTeXt	O
.	O
</s>
<s>
The	O
original	O
source	O
code	O
for	O
the	O
current	O
TeX	B-Application
software	O
is	O
written	O
in	O
WEB	O
,	O
a	O
mixture	O
of	O
documentation	O
written	O
in	O
TeX	B-Application
and	O
a	O
Pascal	B-Application
subset	O
in	O
order	O
to	O
ensure	O
readability	O
and	O
portability	O
.	O
</s>
<s>
For	O
example	O
,	O
TeX	B-Application
does	O
all	O
of	O
its	O
dynamic	O
allocation	O
itself	O
from	O
fixed-size	O
arrays	O
and	O
uses	O
only	O
fixed-point	O
arithmetic	O
for	O
its	O
internal	O
calculations	O
.	O
</s>
<s>
As	O
a	O
result	O
,	O
TeX	B-Application
has	O
been	O
ported	O
to	O
almost	O
all	O
operating	B-General_Concept
systems	I-General_Concept
,	O
usually	O
by	O
using	O
the	O
web2c	B-General_Concept
program	O
to	O
convert	O
the	O
source	O
code	O
into	O
C	B-Language
instead	O
of	O
directly	O
compiling	O
the	O
Pascal	B-Application
code	O
.	O
</s>
<s>
Knuth	O
has	O
kept	O
a	O
very	O
detailed	O
log	O
of	O
all	O
the	O
bugs	B-Error_Name
he	O
has	O
corrected	O
and	O
changes	O
he	O
has	O
made	O
in	O
the	O
program	O
since	O
1982	O
;	O
,	O
the	O
list	O
contains	O
440	O
entries	O
,	O
not	O
including	O
the	O
version	O
modification	O
that	O
should	O
be	O
done	O
after	O
his	O
death	O
as	O
the	O
final	O
change	O
in	O
TeX	B-Application
.	O
</s>
<s>
Knuth	O
offers	O
monetary	O
awards	O
to	O
people	O
who	O
find	O
and	O
report	O
a	O
bug	B-Error_Name
in	O
TeX	B-Application
.	O
</s>
<s>
The	O
award	O
per	O
bug	B-Error_Name
started	O
at	O
US	O
$2.56	O
(	O
one	O
"	O
hexadecimal	O
dollar	O
"	O
)	O
and	O
doubled	O
every	O
year	O
until	O
it	O
was	O
frozen	O
at	O
its	O
current	O
value	O
of	O
$327.68	O
.	O
</s>
<s>
Knuth	O
has	O
lost	O
relatively	O
little	O
money	O
as	O
there	O
have	O
been	O
very	O
few	O
bugs	B-Error_Name
claimed	O
.	O
</s>
<s>
In	O
addition	O
,	O
recipients	O
have	O
been	O
known	O
to	O
frame	O
their	O
cheque	O
as	O
proof	O
that	O
they	O
found	O
a	O
bug	B-Error_Name
in	O
TeX	B-Application
rather	O
than	O
cashing	O
it	O
.	O
</s>
<s>
Due	O
to	O
scammers	O
finding	O
scanned	O
copies	O
of	O
his	O
checks	O
on	O
the	O
internet	O
and	O
using	O
them	O
to	O
try	O
to	O
drain	O
his	O
bank	O
account	O
,	O
Knuth	O
no	O
longer	O
sends	O
out	O
real	O
checks	O
,	O
but	O
those	O
who	O
submit	O
bug	B-Error_Name
reports	O
can	O
get	O
credit	O
at	O
The	O
Bank	O
of	O
San	O
Serriffe	O
instead	O
.	O
</s>
<s>
TeX	B-Application
is	O
usually	O
provided	O
in	O
the	O
form	O
of	O
an	O
easy-to-install	O
bundle	O
of	O
TeX	B-Application
itself	O
along	O
with	O
Metafont	B-Operating_System
and	O
all	O
the	O
necessary	O
fonts	O
,	O
documents	O
formats	O
,	O
and	O
utilities	O
needed	O
to	O
use	O
the	O
typesetting	O
system	O
.	O
</s>
<s>
On	O
UNIX-compatible	O
systems	O
,	O
including	O
Linux	B-Application
and	O
Apple	B-Operating_System
macOS	I-Operating_System
,	O
TeX	B-Application
is	O
distributed	O
as	O
part	O
of	O
the	O
larger	O
TeX	B-General_Concept
Live	I-General_Concept
distribution	O
.	O
</s>
<s>
(	O
Prior	O
to	O
TeX	B-General_Concept
Live	I-General_Concept
,	O
the	O
teTeX	B-General_Concept
distribution	O
was	O
the	O
de	O
facto	O
standard	O
on	O
UNIX-compatible	O
systems	O
.	O
)	O
</s>
<s>
On	O
Microsoft	B-Application
Windows	I-Application
,	O
there	O
is	O
the	O
MiKTeX	B-General_Concept
distribution	O
(	O
enhanced	O
by	O
proTeXt	O
)	O
and	O
the	O
Microsoft	B-Application
Windows	I-Application
version	O
of	O
TeX	B-General_Concept
Live	I-General_Concept
.	O
</s>
<s>
Several	O
document	O
processing	O
systems	O
are	O
based	O
on	O
TeX	B-Application
,	O
notably	O
jadeTeX	O
,	O
which	O
uses	O
TeX	B-Application
as	O
a	O
backend	O
for	O
printing	O
from	O
James	O
Clark	O
's	O
DSSSL	B-Language
Engine	I-Language
,	O
the	O
Arbortext	O
publishing	O
system	O
,	O
and	O
Texinfo	B-Application
,	O
the	O
GNU	B-Operating_System
documentation	O
processing	O
system	O
.	O
</s>
<s>
TeX	B-Application
has	O
been	O
the	O
official	O
typesetting	O
package	O
for	O
the	B-Operating_System
GNU	I-Operating_System
operating	I-Operating_System
system	I-Operating_System
since	O
1984	O
.	O
</s>
<s>
Numerous	O
extensions	O
and	O
companion	O
programs	O
for	O
TeX	B-Application
exist	O
,	O
among	O
them	O
BibTeX	B-Language
for	O
bibliographies	O
(	O
distributed	O
with	O
LaTeX	B-Application
)	O
;	O
pdfTeX	B-Language
,	O
a	O
TeX-compatible	O
engine	O
which	O
can	O
directly	O
produce	O
PDF	B-Application
output	O
(	O
as	O
well	O
as	O
continuing	O
to	O
support	O
the	O
original	O
DVI	B-Application
output	O
)	O
;	O
XeTeX	B-Application
,	O
a	O
TeX-compatible	O
engine	O
that	O
supports	O
Unicode	O
and	O
OpenType	O
;	O
and	O
LuaTeX	B-Language
,	O
a	O
Unicode-aware	O
extension	O
to	O
TeX	B-Application
that	O
includes	O
a	O
Lua	O
runtime	O
with	O
extensive	O
hooks	O
into	O
the	O
underlying	O
TeX	B-Application
routines	O
and	O
algorithms	O
.	O
</s>
<s>
Most	O
TeX	B-Application
extensions	O
are	O
available	O
for	O
free	O
from	O
CTAN	B-General_Concept
,	O
the	O
Comprehensive	B-General_Concept
TeX	I-General_Concept
Archive	I-General_Concept
Network	I-General_Concept
.	O
</s>
<s>
There	O
are	O
a	O
variety	O
of	O
editors	O
designed	O
to	O
work	O
with	O
TeX	B-Application
:	O
</s>
<s>
The	O
TeXmacs	B-Application
text	O
editor	O
is	O
a	O
WYSIWYG-WYSIWYM	O
scientific	O
text	O
editor	O
,	O
inspired	O
by	O
both	O
TeX	B-Application
and	O
Emacs	B-Application
.	O
</s>
<s>
It	O
uses	O
Knuth	O
's	O
fonts	O
and	O
can	O
generate	O
TeX	B-Application
output	O
.	O
</s>
<s>
Overleaf	B-General_Concept
is	O
a	O
partial-WYSIWYG	O
,	O
online	O
editor	O
that	O
provides	O
a	O
cloud-based	O
solution	O
to	O
TeX	B-Application
along	O
with	O
additional	O
features	O
in	O
real-time	O
collaborative	O
editing	O
.	O
</s>
<s>
LyX	B-Language
is	O
a	O
WYSIWYM	B-General_Concept
document	O
processor	O
which	O
runs	O
on	O
a	O
variety	O
of	O
platforms	O
including	O
:	O
</s>
<s>
Linux	B-Application
,	O
</s>
<s>
Apple	B-Operating_System
Mac	I-Operating_System
OS	I-Operating_System
X	I-Operating_System
(	O
using	O
a	O
non-native	O
Qt	B-Language
front-end	O
)	O
.	O
</s>
<s>
TeXShop	B-Language
(	O
for	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
)	O
,	O
TeXworks	B-Operating_System
(	O
for	O
Linux	B-Application
,	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
and	O
Windows	O
)	O
and	O
WinShell	B-Application
(	O
for	O
Windows	O
)	O
are	O
similar	O
tools	O
and	O
provide	O
an	O
integrated	O
development	O
environment	O
(	O
IDE	O
)	O
for	O
working	O
with	O
LaTeX	B-Application
or	O
TeX	B-Application
.	O
</s>
<s>
For	O
KDE/Qt	O
,	O
Kile	B-Language
provides	O
such	O
an	O
IDE	O
.	O
</s>
<s>
Texmaker	O
is	O
the	O
Pure	O
Qt	B-Language
equivalent	O
of	O
Kile	B-Language
,	O
with	O
a	O
user	O
interface	O
that	O
is	O
nearly	O
the	O
same	O
as	O
Kile	B-Language
's	O
.	O
</s>
<s>
TeXstudio	B-General_Concept
is	O
an	O
open-source	O
fork	O
(	O
2009	O
)	O
of	O
Texmaker	O
that	O
offers	O
a	O
different	O
approach	O
to	O
configurability	O
and	O
features	O
.	O
</s>
<s>
Free	O
downloadable	O
binaries	O
are	O
provided	O
for	O
Windows	O
,	O
Linux	B-Application
,	O
Mac	B-Operating_System
OS	I-Operating_System
X	I-Operating_System
,	O
OS/2	O
,	O
and	O
FreeBSD	O
.	O
</s>
<s>
GNU	B-Application
Emacs	I-Application
has	O
various	O
built-in	O
and	O
third-party	O
packages	O
with	O
support	O
for	O
TeX	B-Application
,	O
the	O
major	O
one	O
being	O
AUCTeX	B-Application
.	O
</s>
<s>
Visual	B-Language
Studio	I-Language
Code	I-Language
.	O
</s>
<s>
For	O
Vim	B-Application
,	O
possible	O
plugins	O
include	O
Vim-LaTeX	O
Suite	O
,	O
Automatic	O
TeX	B-Application
and	O
TeX-9	O
.	O
</s>
<s>
For	O
Apache	B-Application
OpenOffice	I-Application
and	O
LibreOffice	B-Application
,	O
iMath	O
and	O
TexMaths	O
extensions	O
can	O
provide	O
mathematical	O
TeX	B-Application
typesetting	O
.	O
</s>
<s>
For	O
MediaWiki	B-Application
,	O
the	O
Math	O
extension	O
provides	O
mathematical	O
TeX	B-Application
typesetting	O
,	O
but	O
the	O
code	O
needs	O
to	O
be	O
surrounded	O
by	O
<math>	O
tag	O
.	O
</s>
<s>
Donald	O
Knuth	O
has	O
indicated	O
several	O
times	O
that	O
the	O
source	O
code	O
of	O
TeX	B-Application
has	O
been	O
placed	O
into	O
the	O
"	O
public	O
domain	O
"	O
,	O
and	O
he	O
strongly	O
encourages	O
modifications	O
or	O
experimentations	O
with	O
this	O
source	O
code	O
.	O
</s>
<s>
However	O
,	O
since	O
Knuth	O
highly	O
values	O
the	O
reproducibility	O
of	O
the	O
output	O
of	O
all	O
versions	O
of	O
TeX	B-Application
,	O
any	O
changed	O
version	O
must	O
not	O
be	O
called	O
TeX	B-Application
,	O
or	O
anything	O
confusingly	O
similar	O
.	O
</s>
<s>
To	O
enforce	O
this	O
rule	O
,	O
any	O
implementation	O
of	O
the	O
system	O
must	O
pass	O
a	O
test	O
suite	O
called	O
the	O
TRIP	O
test	O
before	O
being	O
allowed	O
to	O
be	O
called	O
TeX	B-Application
.	O
</s>
<s>
The	O
question	O
of	O
license	O
is	O
somewhat	O
confused	O
by	O
the	O
statements	O
included	O
at	O
the	O
beginning	O
of	O
the	O
TeX	B-Application
source	O
code	O
,	O
which	O
indicate	O
that	O
"	O
all	O
rights	O
are	O
reserved	O
.	O
</s>
<s>
This	O
restriction	O
should	O
be	O
interpreted	O
as	O
a	O
prohibition	O
to	O
change	O
the	O
source	O
code	O
as	O
long	O
as	O
the	O
file	O
is	O
called	O
tex.web	O
.	O
</s>
<s>
The	O
copyright	O
note	O
at	O
the	O
beginning	O
of	O
tex.web	O
(	O
and	O
mf.web	O
)	O
was	O
changed	O
in	O
2021	O
to	O
explicitly	O
state	O
this	O
.	O
</s>
<s>
This	O
interpretation	O
is	O
confirmed	O
later	O
in	O
the	O
source	O
code	O
when	O
the	O
TRIP	O
test	O
is	O
mentioned	O
(	O
"	O
If	O
this	O
program	O
is	O
changed	O
,	O
the	O
resulting	O
system	O
should	O
not	O
be	O
called	O
'	O
TeX	B-Application
)	O
.	O
</s>
<s>
The	O
American	O
Mathematical	O
Society	O
tried	O
in	O
the	O
early	O
1980s	O
to	O
claim	O
a	O
trademark	O
for	O
TeX	B-Application
.	O
</s>
<s>
This	O
was	O
rejected	O
because	O
at	O
the	O
time	O
"	O
TEX	B-Application
"	O
(	O
all	O
caps	O
)	O
was	O
registered	O
by	O
Honeywell	O
for	O
the	O
"	O
Text	B-Language
EXecutive	I-Language
"	O
text	O
processing	O
system	O
.	O
</s>
<s>
It	O
is	O
possible	O
to	O
use	O
TeX	B-Application
for	O
automatic	O
generation	O
of	O
sophisticated	O
layout	O
for	O
XML	O
data	O
.	O
</s>
<s>
The	O
differences	O
in	O
syntax	O
between	O
the	O
two	O
description	O
languages	O
can	O
be	O
overcome	O
with	O
the	O
help	O
of	O
TeXML	B-Language
.	O
</s>
<s>
In	O
the	O
context	O
of	O
XML	O
publication	O
,	O
TeX	B-Application
can	O
thus	O
be	O
considered	O
an	O
alternative	O
to	O
XSL-FO	B-Language
.	O
</s>
<s>
TeX	B-Application
allowed	O
scientific	O
papers	O
in	O
mathematical	O
disciplines	O
to	O
be	O
reduced	O
to	O
relatively	O
small	O
files	O
that	O
could	O
be	O
rendered	O
client-side	O
,	O
allowing	O
fully	O
typeset	O
scientific	O
papers	O
to	O
be	O
exchanged	O
over	O
the	O
early	O
Internet	O
and	O
emerging	O
World	O
Wide	O
Web	O
,	O
even	O
when	O
sending	O
large	O
files	O
was	O
difficult	O
.	O
</s>
<s>
The	O
name	O
TeX	B-Application
is	O
intended	O
by	O
its	O
developer	O
to	O
be	O
,	O
with	O
the	O
final	O
consonant	O
of	O
loch	O
.	O
</s>
<s>
The	O
letters	O
of	O
the	O
name	O
are	O
meant	O
to	O
represent	O
the	O
capital	O
Greek	O
letters	O
tau	O
,	O
epsilon	B-Language
,	O
and	O
chi	O
,	O
as	O
TeX	B-Application
is	O
an	O
abbreviation	O
of	O
τέχνη	O
(	O
)	O
,	O
Greek	O
for	O
both	O
"	O
art	O
"	O
and	O
"	O
craft	O
"	O
,	O
which	O
is	O
also	O
the	O
root	O
word	O
of	O
technical	O
.	O
</s>
<s>
This	O
is	O
done	O
,	O
as	O
Knuth	O
mentions	O
in	O
his	O
TeXbook	O
,	O
to	O
distinguish	O
TeX	B-Application
from	O
other	O
system	O
names	O
such	O
as	O
TEX	B-Language
,	I-Language
the	I-Language
Text	I-Language
EXecutive	I-Language
processor	I-Language
(	O
developed	O
by	O
Honeywell	O
Information	O
Systems	O
)	O
.	O
</s>
<s>
Fans	O
like	O
to	O
proliferate	O
names	O
from	O
the	O
word	O
"	O
TeX	B-Application
"	O
—	O
such	O
as	O
TeXnician	O
(	O
user	O
of	O
TeX	B-Application
software	O
)	O
,	O
TeXhacker	O
(	O
TeX	B-Application
programmer	O
)	O
,	O
TeXmaster	O
(	O
competent	O
TeX	B-Application
programmer	O
)	O
,	O
TeXhax	O
,	O
and	O
TeXnique	O
.	O
</s>
<s>
Notable	O
entities	O
in	O
the	O
TeX	B-Application
community	O
include	O
the	O
TeX	B-Application
Users	O
Group	O
(	O
TUG	O
)	O
,	O
which	O
publishes	O
TUGboat	O
and	O
The	O
PracTeX	O
Journal	O
,	O
covering	O
a	O
wide	O
range	O
of	O
topics	O
in	O
digital	O
typography	O
relevant	O
to	O
TeX	B-Application
.	O
</s>
<s>
The	O
Deutschsprachige	O
Anwendervereinigung	O
TeX	B-Application
(	O
DANTE	O
)	O
is	O
a	O
large	O
user	O
group	O
in	O
Germany	O
.	O
</s>
<s>
The	O
TeX	B-Application
Users	O
Group	O
was	O
founded	O
in	O
1980	O
for	O
educational	O
and	O
scientific	O
purposes	O
,	O
provides	O
an	O
organization	O
for	O
those	O
who	O
have	O
an	O
interest	O
in	O
typography	O
and	O
font	O
design	O
,	O
and	O
are	O
users	O
of	O
the	O
TeX	B-Application
typesetting	O
system	O
invented	O
by	O
Knuth	O
.	O
</s>
<s>
The	O
TeX	B-Application
Users	O
Group	O
represents	O
the	O
interests	O
of	O
TeX	B-Application
users	O
worldwide	O
.	O
</s>
<s>
The	O
TeX	B-Application
Users	O
Group	O
publishes	O
the	O
journal	O
TUGboat	O
three	O
times	O
per	O
year	O
;	O
DANTE	O
publishes	O
four	O
times	O
per	O
year	O
.	O
</s>
