<s>
XSLT	B-Application
(	O
Extensible	B-Application
Stylesheet	I-Application
Language	I-Application
Transformations	I-Application
)	O
is	O
a	O
language	O
originally	O
designed	O
for	O
transforming	B-Language
XML	B-Protocol
documents	I-Protocol
into	O
other	O
XML	B-Protocol
documents	I-Protocol
,	O
or	O
other	O
formats	O
such	O
as	O
HTML	B-Language
for	O
web	O
pages	O
,	O
plain	O
text	O
or	O
XSL	B-Language
Formatting	I-Language
Objects	I-Language
,	O
which	O
may	O
subsequently	O
be	O
converted	O
to	O
other	O
formats	O
,	O
such	O
as	O
PDF	B-Application
,	O
PostScript	B-Language
and	O
PNG	O
.	O
</s>
<s>
Support	O
for	O
JSON	O
and	O
plain-text	O
transformation	O
was	O
added	O
in	O
later	O
updates	O
to	O
the	O
XSLT	B-Application
1.0	O
specification	O
.	O
</s>
<s>
As	O
of	O
August	O
2022	O
,	O
the	O
most	O
recent	O
stable	O
version	O
of	O
the	O
language	O
is	O
XSLT	B-Application
3.0	O
,	O
which	O
achieved	O
Recommendation	O
status	O
in	O
June	O
2017	O
.	O
</s>
<s>
XSLT	B-Application
3.0	O
implementations	O
support	O
Java	B-Language
,	O
.NET	O
,	O
C/C	O
++	O
,	O
Python	B-Language
,	O
PHP	B-Application
and	O
NodeJS	B-Language
.	O
</s>
<s>
An	O
XSLT	B-Application
3.0	O
Javascript	B-Language
library	B-Library
can	O
also	O
be	O
hosted	O
within	O
the	O
Web	B-Application
Browser	I-Application
.	O
</s>
<s>
Modern	O
web	B-Application
browsers	I-Application
also	O
include	O
native	O
support	O
for	O
XSLT	B-Application
1.0	O
.	O
</s>
<s>
For	O
an	O
XSLT	B-Application
document	O
transformation	O
,	O
the	O
original	O
document	O
is	O
not	O
changed	O
;	O
rather	O
,	O
a	O
new	O
document	O
is	O
created	O
based	O
on	O
the	O
content	O
of	O
an	O
existing	O
one	O
.	O
</s>
<s>
Typically	O
,	O
input	O
documents	O
are	O
XML	B-Protocol
files	O
,	O
but	O
anything	O
from	O
which	O
the	O
processor	O
can	O
build	O
an	O
XQuery	B-Application
and	I-Application
XPath	I-Application
Data	I-Application
Model	I-Application
can	O
be	O
used	O
,	O
such	O
as	O
relational	B-Application
database	I-Application
tables	O
or	O
geographical	B-Application
information	I-Application
systems	I-Application
.	O
</s>
<s>
While	O
XSLT	B-Application
was	O
originally	O
designed	O
as	O
a	O
special-purpose	O
language	O
for	O
XML	B-Language
transformation	I-Language
,	O
the	O
language	O
is	O
Turing-complete	B-Algorithm
,	O
making	O
it	O
theoretically	O
capable	O
of	O
arbitrary	O
computations	O
.	O
</s>
<s>
XSLT	B-Application
is	O
influenced	O
by	O
functional	B-Language
languages	I-Language
,	O
and	O
by	O
text-based	O
pattern	O
matching	O
languages	O
like	O
SNOBOL	B-Application
and	O
AWK	B-Application
.	O
</s>
<s>
Its	O
most	O
direct	O
predecessor	O
is	O
DSSSL	B-Language
,	O
which	O
did	O
for	O
SGML	B-Language
what	O
XSLT	B-Application
does	O
for	O
XML	B-Protocol
.	O
</s>
<s>
XSLT	B-Application
1.0	O
:	O
XSLT	B-Application
was	O
part	O
of	O
the	O
World	O
Wide	O
Web	O
Consortium	O
(	O
W3C	O
)	O
'	O
s	O
eXtensible	B-Language
Stylesheet	I-Language
Language	I-Language
(	O
XSL	B-Language
)	O
development	O
effort	O
of	O
1998	O
–	O
1999	O
,	O
a	O
project	O
that	O
also	O
produced	O
XSL-FO	B-Language
and	O
XPath	B-Language
.	O
</s>
<s>
Some	O
members	O
of	O
the	O
standards	O
committee	O
that	O
developed	O
XSLT	B-Application
,	O
including	O
James	O
Clark	O
,	O
the	O
editor	O
,	O
had	O
previously	O
worked	O
on	O
DSSSL	B-Language
.	O
</s>
<s>
XSLT	B-Application
1.0	O
was	O
published	O
as	O
a	O
W3C	O
recommendation	O
in	O
November	O
1999	O
.	O
</s>
<s>
Despite	O
its	O
age	O
,	O
XSLT	B-Application
1.0	O
is	O
still	O
widely	O
used	O
(	O
)	O
,	O
since	O
later	O
versions	O
are	O
not	O
supported	O
natively	O
in	O
web	B-Application
browsers	I-Application
or	O
for	O
environments	O
like	O
LAMP	B-Application
.	O
</s>
<s>
XSLT	B-Application
2.0	I-Application
:	O
after	O
an	O
abortive	O
attempt	O
to	O
create	O
a	O
version	O
1.1	O
in	O
2001	O
,	O
the	O
XSL	B-Language
working	O
group	O
joined	O
forces	O
with	O
the	O
XQuery	B-Language
working	O
group	O
to	O
create	O
XPath	B-General_Concept
2.0	I-General_Concept
,	O
with	O
a	O
richer	O
data	O
model	O
and	O
type	O
system	O
based	O
on	O
XML	B-Protocol
Schema	O
.	O
</s>
<s>
Building	O
on	O
this	O
is	O
XSLT	B-Application
2.0	I-Application
,	O
developed	O
under	O
the	O
editorship	O
of	O
Michael	O
Kay	O
,	O
which	O
reached	O
recommendation	O
status	O
in	O
January	O
2007	O
.	O
</s>
<s>
The	O
most	O
important	O
innovations	O
in	O
XSLT	B-Application
2.0	I-Application
include	O
:	O
</s>
<s>
XSLT	B-Application
3.0	O
:	O
became	O
a	O
W3C	O
Recommendation	O
on	O
8	O
June	O
2017	O
.	O
</s>
<s>
Streaming	B-Language
transformations	I-Language
:	O
in	O
previous	O
versions	O
the	O
entire	O
input	O
document	O
had	O
to	O
be	O
read	O
into	O
memory	O
before	O
it	O
could	O
be	O
processed	O
,	O
and	O
output	O
could	O
not	O
be	O
written	O
until	O
processing	O
had	O
finished	O
.	O
</s>
<s>
XSLT	B-Application
3.0	O
allows	O
XML	B-Language
streaming	I-Language
which	O
is	O
useful	O
for	O
processing	O
documents	O
too	O
large	O
to	O
fit	O
in	O
memory	O
or	O
when	O
transformations	O
are	O
chained	O
in	O
XML	B-Operating_System
Pipelines	I-Operating_System
.	O
</s>
<s>
Improved	O
handling	O
of	O
dynamic	O
errors	O
with	O
,	O
for	O
example	O
,	O
an	O
xsl:try	O
instruction	O
.	O
</s>
<s>
Support	O
for	O
maps	O
and	O
arrays	O
,	O
enabling	O
XSLT	B-Application
to	O
handle	O
JSON	O
as	O
well	O
as	O
XML	B-Protocol
.	O
</s>
<s>
The	O
XSLT	B-Application
processor	I-Application
takes	O
one	O
or	O
more	O
XML	B-Protocol
source	O
documents	O
,	O
plus	O
one	O
or	O
more	O
XSLT	B-Application
stylesheets	O
,	O
and	O
processes	O
them	O
to	O
produce	O
one	O
or	O
multiple	O
output	O
documents	O
.	O
</s>
<s>
In	O
contrast	O
to	O
widely	O
implemented	O
imperative	B-Application
programming	I-Application
languages	I-Application
like	O
C	B-Language
,	O
XSLT	B-Application
is	O
declarative	B-Language
.	O
</s>
<s>
Rather	O
than	O
listing	O
an	O
imperative	B-Application
sequence	O
of	O
actions	O
to	O
perform	O
in	O
a	O
stateful	O
environment	O
,	O
template	O
rules	O
only	O
define	O
how	O
to	O
handle	O
a	O
node	O
matching	O
a	O
particular	O
XPath-like	O
pattern	O
,	O
if	O
the	O
processor	O
should	O
happen	O
to	O
encounter	O
one	O
,	O
and	O
the	O
contents	O
of	O
the	O
templates	O
effectively	O
comprise	O
functional	B-Language
expressions	O
that	O
directly	O
represent	O
their	O
evaluated	O
form	O
:	O
the	O
result	O
tree	B-Application
,	O
which	O
is	O
the	O
basis	O
of	O
the	O
processor	O
's	O
output	O
.	O
</s>
<s>
First	O
,	O
assuming	O
a	O
stylesheet	O
has	O
already	O
been	O
read	O
and	O
prepared	O
,	O
the	O
processor	O
builds	O
a	O
source	O
tree	B-Application
from	O
the	O
input	O
XML	B-Protocol
document	I-Protocol
.	O
</s>
<s>
It	O
then	O
processes	O
the	O
source	O
tree	B-Application
's	O
root	B-Application
node	I-Application
,	O
finds	O
the	O
best-matching	O
template	O
for	O
that	O
node	O
in	O
the	O
stylesheet	O
,	O
and	O
evaluates	O
the	O
template	O
's	O
contents	O
.	O
</s>
<s>
Instructions	O
in	O
each	O
template	O
generally	O
direct	O
the	O
processor	O
to	O
either	O
create	O
nodes	O
in	O
the	O
result	O
tree	B-Application
,	O
or	O
to	O
process	O
more	O
nodes	O
in	O
the	O
source	O
tree	B-Application
in	O
the	O
same	O
way	O
as	O
the	O
root	B-Application
node	I-Application
.	O
</s>
<s>
Finally	O
the	O
result	O
tree	B-Application
is	O
serialized	O
as	O
XML	B-Protocol
or	O
HTML	B-Language
text	O
.	O
</s>
<s>
XSLT	B-Application
uses	O
XPath	B-Language
to	O
identify	O
subsets	O
of	O
the	O
source	O
document	O
tree	B-Application
and	O
perform	O
calculations	O
.	O
</s>
<s>
XPath	B-Language
also	O
provides	O
a	O
range	O
of	O
functions	O
,	O
which	O
XSLT	B-Application
itself	O
further	O
augments	O
.	O
</s>
<s>
XSLT	B-Application
1.0	O
uses	O
XPath	B-Language
1.0	I-Language
,	O
while	O
XSLT	B-Application
2.0	I-Application
uses	O
XPath	B-General_Concept
2.0	I-General_Concept
.	O
</s>
<s>
XSLT	B-Application
3.0	O
will	O
work	O
with	O
either	O
XPath	B-Language
3.0	O
or	O
3.1	O
.	O
</s>
<s>
In	O
the	O
case	O
of	O
1.0	O
and	O
2.0	O
,	O
the	O
XSLT	B-Application
and	O
XPath	B-Language
specifications	O
were	O
published	O
on	O
the	O
same	O
date	O
.	O
</s>
<s>
With	O
3.0	O
,	O
however	O
,	O
they	O
were	O
no	O
longer	O
synchronized	O
;	O
XPath	B-Language
3.0	O
became	O
a	O
Recommendation	O
in	O
April	O
2014	O
,	O
followed	O
by	O
XPath	B-Language
3.1	O
in	O
February	O
2017	O
;	O
XSLT	B-Application
3.0	O
followed	O
in	O
June	O
2017	O
.	O
</s>
<s>
XSLT	B-Application
functionalities	O
overlap	O
with	O
those	O
of	O
XQuery	B-Language
,	O
which	O
was	O
initially	O
conceived	O
as	O
a	O
query	B-Language
language	I-Language
for	O
large	O
collections	O
of	O
XML	B-Protocol
documents	I-Protocol
.	O
</s>
<s>
The	O
XSLT	B-Application
2.0	I-Application
and	O
XQuery	B-Language
1.0	O
standards	O
were	O
developed	O
by	O
separate	O
working	O
groups	O
within	O
W3C	O
,	O
working	O
together	O
to	O
ensure	O
a	O
common	O
approach	O
where	O
appropriate	O
.	O
</s>
<s>
They	O
share	O
the	O
same	O
data	O
model	O
,	O
type	O
system	O
,	O
and	O
function	B-Library
library	I-Library
,	O
and	O
both	O
include	O
XPath	B-General_Concept
2.0	I-General_Concept
as	O
a	O
sublanguage	O
.	O
</s>
<s>
XSLT	B-Application
was	O
primarily	O
conceived	O
as	O
a	O
stylesheet	O
language	O
whose	O
primary	O
goal	O
was	O
to	O
render	O
XML	B-Protocol
for	O
the	O
human	O
reader	O
on	O
screen	O
,	O
on	O
the	O
web	O
(	O
as	O
a	O
web	B-Application
template	I-Application
language	I-Application
)	O
,	O
or	O
on	O
paper	O
.	O
</s>
<s>
XQuery	B-Language
was	O
primarily	O
conceived	O
as	O
a	O
database	B-Language
query	I-Language
language	I-Language
in	O
the	O
tradition	O
of	O
SQL	B-Language
.	O
</s>
<s>
of	O
narrative	O
documents	O
with	O
more	O
flexible	O
structure	O
,	O
while	O
XQuery	B-Language
is	O
stronger	O
in	O
its	O
data	O
handling	O
,	O
for	O
example	O
when	O
performing	O
relational	O
joins	O
.	O
</s>
<s>
The	O
<output> element can optionally take the attribute media-type, which allows one to set the media type (or MIME type )  for the resulting output, for example: <xsl:output output="xml" media-type="application/xml"/>	O
.	O
</s>
<s>
The	O
XSLT	B-Application
1.0	O
recommendation	O
recommends	O
the	O
more	O
general	O
attribute	O
types	O
text/xml	B-Protocol
and	O
application/xml	O
since	O
for	O
a	O
long	O
time	O
there	O
was	O
no	O
registered	O
media	B-Application
type	I-Application
for	O
XSLT	B-Application
.	O
</s>
<s>
During	O
this	O
time	O
text/xsl	O
became	O
the	O
de	O
facto	O
standard	O
.	O
</s>
<s>
In	O
XSLT	B-Application
1.0	O
it	O
was	O
not	O
specified	O
how	O
the	O
media-type	O
values	O
should	O
be	O
used	O
.	O
</s>
<s>
With	O
the	O
release	O
of	O
the	O
XSLT	B-Application
2.0	I-Application
,	O
the	O
W3C	O
recommended	O
the	O
registration	O
of	O
the	O
MIME	O
media	B-Application
type	I-Application
application/xslt	O
+xml	O
and	O
it	O
was	O
later	O
registered	O
with	O
the	O
Internet	O
Assigned	O
Numbers	O
Authority	O
.	O
</s>
<s>
Pre-1.0	O
working	O
drafts	O
of	O
XSLT	B-Application
used	O
text/xsl	O
in	O
their	O
embedding	O
examples	O
,	O
and	O
this	O
type	O
was	O
implemented	O
and	O
continues	O
to	O
be	O
promoted	O
by	O
Microsoft	O
in	O
Internet	O
Explorer	O
and	O
MSXML	B-Application
.	O
</s>
<s>
It	O
is	O
also	O
widely	O
recognized	O
in	O
the	O
xml-stylesheet	O
processing	O
instruction	O
by	O
other	O
browsers	B-Application
.	O
</s>
<s>
In	O
practice	O
,	O
therefore	O
,	O
users	O
wanting	O
to	O
control	O
transformation	O
in	O
the	O
browser	B-Application
using	O
this	O
processing	O
instruction	O
are	O
obliged	O
to	O
use	O
this	O
unregistered	O
media	B-Application
type	I-Application
.	O
</s>
<s>
This	O
XSLT	B-Application
stylesheet	O
provides	O
templates	O
to	O
transform	O
the	O
XML	B-Protocol
document	I-Protocol
:	O
</s>
<s>
Its	O
evaluation	O
results	O
in	O
a	O
new	O
XML	B-Protocol
document	I-Protocol
,	O
having	O
another	O
structure	O
:	O
</s>
<s>
with	O
the	O
XML	B-Protocol
input	O
file	O
shown	O
above	O
results	O
in	O
the	O
following	O
XHTML	B-Language
(	O
whitespace	O
has	O
been	O
adjusted	O
here	O
for	O
clarity	O
)	O
:	O
</s>
<s>
This	O
XHTML	B-Language
generates	O
the	O
output	O
below	O
when	O
rendered	O
in	O
a	O
web	B-Application
browser	I-Application
.	O
</s>
<s>
In	O
order	O
for	O
a	O
web	B-Application
browser	I-Application
to	O
be	O
able	O
to	O
apply	O
an	O
XSL	B-Application
transformation	I-Application
to	O
an	O
XML	B-Protocol
document	I-Protocol
on	O
display	O
,	O
an	O
XML	B-Protocol
stylesheet	O
processing	O
instruction	O
can	O
be	O
inserted	O
into	O
XML	B-Protocol
.	O
</s>
<s>
So	O
,	O
for	O
example	O
,	O
if	O
the	O
stylesheet	O
in	O
Example	O
2	O
above	O
were	O
available	O
as	O
"	O
example2.xsl	O
"	O
,	O
the	O
following	O
instruction	O
could	O
be	O
added	O
to	O
the	O
original	O
incoming	O
XML	B-Protocol
:	O
</s>
<s>
In	O
this	O
example	O
,	O
text/xsl	O
is	O
technically	O
incorrect	O
according	O
to	O
the	O
W3C	O
specifications	O
(	O
which	O
say	O
the	O
type	O
should	O
be	O
application/xslt	O
+xml	O
)	O
,	O
but	O
it	O
is	O
the	O
only	O
media	B-Application
type	I-Application
that	O
is	O
widely	O
supported	O
across	O
browsers	B-Application
as	O
of	O
2009	O
,	O
and	O
the	O
situation	O
is	O
unchanged	O
in	O
2021	O
.	O
</s>
<s>
RaptorXML	O
from	O
Altova	O
is	O
an	O
XSLT	B-Application
3.0	O
processor	O
available	O
in	O
the	O
XMLSpy	O
development	O
toolkit	O
and	O
as	O
a	O
free-standing	O
server	O
implementation	O
,	O
invoked	O
using	O
a	O
REST	O
interface	O
.	O
</s>
<s>
IBM	O
offers	O
XSLT	B-Application
processing	O
embedded	O
in	O
a	O
special-purpose	O
hardware	O
appliance	O
under	O
the	O
Datapower	B-Device
brand	O
.	O
</s>
<s>
libxslt	B-Language
is	O
a	O
free	B-Application
library	B-Library
released	O
under	O
the	B-License
MIT	I-License
License	I-License
that	O
can	O
be	O
reused	O
in	O
commercial	O
applications	O
.	O
</s>
<s>
It	O
is	O
based	O
on	O
libxml	B-Application
and	O
implemented	O
in	O
C	B-Language
for	O
speed	O
and	O
portability	O
.	O
</s>
<s>
It	O
supports	O
XSLT	B-Application
1.0	O
and	O
EXSLT	B-Language
extensions	O
.	O
</s>
<s>
It	O
can	O
be	O
used	O
at	O
the	O
command	O
line	O
via	O
xsltproc	B-Language
which	O
is	O
included	O
in	O
macOS	B-Application
and	O
many	O
Linux	B-Application
distributions	I-Application
,	O
and	O
can	O
be	O
used	O
on	O
Windows	B-Application
via	O
Cygwin	B-Language
.	O
</s>
<s>
The	O
WebKit	B-Language
and	O
Blink	B-Language
layout	I-Language
engines	I-Language
,	O
used	O
for	O
example	O
in	O
the	O
Safari	B-Application
and	O
Chrome	B-Application
web	I-Application
browsers	I-Application
respectively	O
,	O
uses	O
the	O
libxslt	B-Language
library	B-Library
to	O
do	O
XSL	B-Application
transformations	I-Application
.	O
</s>
<s>
Bindings	B-Application
exist	O
for	O
Python	B-Language
,	O
Perl	B-Language
,	O
Ruby	B-Language
,	O
PHP	B-Application
,	O
Common	B-Language
Lisp	I-Language
,	O
Tcl	B-Operating_System
,	O
and	O
C++	B-Language
.	O
</s>
<s>
Microsoft	O
provides	O
two	O
XSLT	B-Application
processors	I-Application
(	O
both	O
XSLT	B-Application
1.0	O
only	O
)	O
.	O
</s>
<s>
The	O
earlier	O
processor	O
MSXML	B-Application
provides	O
COM	O
interfaces	O
;	O
from	O
MSXML	B-Application
4.0	O
it	O
also	O
includes	O
the	O
command	O
line	O
utility	O
msxsl.exe	O
.	O
</s>
<s>
The	O
.NET	O
runtime	O
includes	O
a	O
separate	O
built-in	O
XSLT	B-Application
processor	I-Application
in	O
its	O
System.Xml.Xsl	O
library	B-Library
.	O
</s>
<s>
Saxon	B-Language
is	O
an	O
XSLT	B-Application
3.0	O
and	O
XQuery	B-Language
3.1	O
processor	O
with	O
open-source	B-Application
and	O
proprietary	B-Application
versions	O
for	O
stand-alone	O
operation	O
and	O
for	O
Java	B-Language
,	O
JavaScript	B-Language
and	O
.NET	O
.	O
</s>
<s>
A	O
separate	O
product	O
Saxon-JS	O
offers	O
XSLT	B-Application
3.0	O
processing	O
on	O
Node.js	B-Language
and	O
in	O
the	O
browser	B-Application
.	O
</s>
<s>
Xalan	B-Language
is	O
an	O
open	O
source	O
XSLT	B-Application
1.0	O
processor	O
from	O
the	O
Apache	O
Software	O
Foundation	O
available	O
for	O
Java	B-Language
and	O
C++	B-Language
.	O
</s>
<s>
A	O
variant	O
of	O
the	O
Xalan	B-Language
processor	O
is	O
included	O
as	O
the	O
default	O
XSLT	B-Application
processor	I-Application
in	O
the	O
standard	O
Java	B-Language
distribution	O
from	O
Oracle	O
.	O
</s>
<s>
Web	B-Application
browsers	I-Application
:	O
Safari	B-Application
,	O
Chrome	B-Application
,	O
Firefox	O
,	O
Opera	O
and	O
Internet	O
Explorer	O
all	O
support	O
XSLT	B-Application
1.0	O
(	O
only	O
)	O
.	O
</s>
<s>
Browsers	B-Application
can	O
perform	O
on-the-fly	O
transformations	O
of	O
XML	B-Protocol
files	O
and	O
display	O
the	O
transformation	O
output	O
in	O
the	O
browser	B-Application
window	O
.	O
</s>
<s>
This	O
is	O
done	O
either	O
by	O
embedding	O
the	O
XSL	B-Language
in	O
the	O
XML	B-Protocol
document	I-Protocol
or	O
by	O
referencing	O
a	O
file	O
containing	O
XSL	B-Language
instructions	O
from	O
the	O
XML	B-Protocol
document	I-Protocol
.	O
</s>
<s>
The	O
latter	O
may	O
not	O
work	O
with	O
Chrome	B-Application
on	O
files	O
from	O
local	O
filesystem	O
because	O
of	O
its	O
security	O
model	O
.	O
</s>
<s>
Most	O
early	O
XSLT	B-Application
processors	I-Application
were	O
interpreters	O
.	O
</s>
<s>
More	O
recently	O
,	O
code	O
generation	O
is	O
increasingly	O
common	O
,	O
using	O
portable	O
intermediate	O
languages	O
(	O
such	O
as	O
Java	B-Language
bytecode	I-Language
or	O
.NET	O
Common	O
Intermediate	O
Language	O
)	O
as	O
the	O
target	O
.	O
</s>
<s>
However	O
,	O
even	O
the	O
interpretive	O
products	O
generally	O
offer	O
separate	O
analysis	O
and	O
execution	O
phases	O
,	O
allowing	O
an	O
optimized	O
expression	O
tree	B-Application
to	O
be	O
created	O
in	O
memory	O
and	O
reused	O
to	O
perform	O
multiple	O
transformations	O
.	O
</s>
<s>
This	O
separation	O
is	O
reflected	O
in	O
the	O
design	O
of	O
XSLT	B-Application
processing	O
APIs	O
(	O
such	O
as	O
JAXP	B-Language
)	O
.	O
</s>
<s>
Early	O
XSLT	B-Application
processors	I-Application
had	O
very	O
few	O
optimizations	O
.	O
</s>
<s>
Stylesheet	O
documents	O
were	O
read	O
into	O
Document	B-General_Concept
Object	I-General_Concept
Models	I-General_Concept
and	O
the	O
processor	O
would	O
act	O
on	O
them	O
directly	O
.	O
</s>
<s>
XPath	B-Language
engines	O
were	O
also	O
not	O
optimized	O
.	O
</s>
<s>
Increasingly	O
,	O
however	O
,	O
XSLT	B-Application
processors	I-Application
use	O
optimization	O
techniques	O
found	O
in	O
functional	B-Language
programming	I-Language
languages	I-Language
and	O
database	B-Language
query	I-Language
languages	I-Language
,	O
such	O
as	O
static	O
rewriting	O
of	O
an	O
expression	O
tree	B-Application
(	O
e.g.	O
,	O
to	O
move	O
calculations	O
out	O
of	O
loops	O
)	O
,	O
and	O
lazy	O
pipelined	O
evaluation	O
to	O
reduce	O
the	O
memory	O
footprint	O
of	O
intermediate	O
results	O
(	O
and	O
allow	O
"	O
early	O
exit	O
"	O
when	O
the	O
processor	O
can	O
evaluate	O
an	O
expression	O
such	O
as	O
following-sibling::*[1]	O
without	O
a	O
complete	O
evaluation	O
of	O
all	O
subexpressions	O
)	O
.	O
</s>
<s>
Many	O
processors	O
also	O
use	O
tree	B-Application
representations	O
that	O
are	O
significantly	O
more	O
efficient	O
(	O
in	O
both	O
space	O
and	O
time	O
)	O
than	O
general-purpose	O
DOM	B-General_Concept
implementations	O
.	O
</s>
<s>
In	O
June	O
2014	O
,	O
Debbie	O
Lockett	O
and	O
Michael	O
Kay	O
introduced	O
an	O
open-source	B-Application
benchmarking	O
framework	O
for	O
XSLT	B-Application
processors	I-Application
called	O
XT-Speedo	O
.	O
</s>
