<s>
A	O
processing	B-Language
instruction	I-Language
(	O
PI	O
)	O
is	O
an	O
SGML	B-Language
and	O
XML	B-Protocol
node	O
type	O
,	O
which	O
may	O
occur	O
anywhere	O
in	O
a	O
document	O
,	O
intended	O
to	O
carry	O
instructions	O
to	O
the	O
application	O
.	O
</s>
<s>
Processing	B-Language
instructions	I-Language
are	O
exposed	O
in	O
the	O
Document	B-General_Concept
Object	I-General_Concept
Model	I-General_Concept
as	O
Node.PROCESSING_INSTRUCTION_NODE	O
,	O
and	O
they	O
can	O
be	O
used	O
in	O
XPath	B-Language
and	O
XQuery	B-Language
with	O
the	O
'	O
processing-instruction( )	O
'	O
command	O
.	O
</s>
<s>
An	O
SGML	B-Language
processing	B-Language
instruction	I-Language
is	O
enclosed	O
within	O
<	O
?	O
</s>
<s>
An	O
XML	B-Protocol
processing	B-Language
instruction	I-Language
is	O
enclosed	O
within	O
<	O
?	O
</s>
<s>
The	O
XML	B-Protocol
Declaration	O
at	O
the	O
beginning	O
of	O
an	O
XML	B-Protocol
document	I-Protocol
(	O
shown	O
below	O
)	O
is	O
another	O
example	O
of	O
a	O
processing	B-Language
instruction	I-Language
,	O
however	O
it	O
may	O
not	O
technically	O
be	O
considered	O
one	O
.	O
</s>
<s>
The	O
most	O
common	O
use	O
of	O
a	O
processing	B-Language
instruction	I-Language
is	O
to	O
request	O
the	O
XML	B-Protocol
document	I-Protocol
be	O
rendered	O
using	O
a	O
stylesheet	B-Language
using	O
the	O
'	O
xml-stylesheet	O
'	O
target	O
,	O
which	O
was	O
standardized	O
in	O
1999	O
.	O
</s>
<s>
It	O
can	O
be	O
used	O
for	O
both	O
XSLT	B-Application
and	O
CSS	B-Language
stylesheets	I-Language
.	O
</s>
<s>
The	O
DocBook	B-Protocol
XSLT	B-Application
stylesheets	O
understand	O
a	O
number	O
of	O
processing	B-Language
instructions	I-Language
to	O
override	O
the	O
default	O
behaviour	O
.	O
</s>
<s>
A	O
draft	O
specification	O
for	O
Robots	O
exclusion	O
standard	O
rules	O
inside	O
XML	B-Protocol
documents	I-Protocol
uses	O
processing	B-Language
instructions	I-Language
.	O
</s>
