A processing instruction (PI) is an SGML and XML node type, which may occur anywhere in a document, intended to carry instructions to the application. [1] [2]
Processing instructions are exposed in the
Document Object Model as Node.PROCESSING_INSTRUCTION_NODE
, and they can be used in
XPath and
XQuery with the 'processing-instruction()' command.
An SGML processing instruction is enclosed within <?
and >
.
[3]
An XML processing instruction is enclosed within <?
and ?>
, and contains a target and optionally some content, which is the node value, that cannot contain the sequence ?>
.
[4]
<?PITarget PIContent?>
The XML Declaration at the beginning of an XML document (shown below) is another example of a processing instruction, [5] however it may not technically be considered one. [6]
<?xml version="1.0" encoding="UTF-8" ?>
The most common use of a processing instruction is to request the XML document be rendered using a stylesheet using the 'xml-stylesheet' target, which was standardized in 1999. [7] It can be used for both XSLT and CSS stylesheets.
<?xml-stylesheet type="text/xsl" href="style.xsl"?>
<?xml-stylesheet type="text/css" href="style.css"?>
The DocBook XSLT stylesheets understand a number of processing instructions to override the default behaviour. [8]
A draft specification for Robots exclusion standard rules inside XML documents uses processing instructions. [9]
A processing instruction (PI) is an SGML and XML node type, which may occur anywhere in a document, intended to carry instructions to the application. [1] [2]
Processing instructions are exposed in the
Document Object Model as Node.PROCESSING_INSTRUCTION_NODE
, and they can be used in
XPath and
XQuery with the 'processing-instruction()' command.
An SGML processing instruction is enclosed within <?
and >
.
[3]
An XML processing instruction is enclosed within <?
and ?>
, and contains a target and optionally some content, which is the node value, that cannot contain the sequence ?>
.
[4]
<?PITarget PIContent?>
The XML Declaration at the beginning of an XML document (shown below) is another example of a processing instruction, [5] however it may not technically be considered one. [6]
<?xml version="1.0" encoding="UTF-8" ?>
The most common use of a processing instruction is to request the XML document be rendered using a stylesheet using the 'xml-stylesheet' target, which was standardized in 1999. [7] It can be used for both XSLT and CSS stylesheets.
<?xml-stylesheet type="text/xsl" href="style.xsl"?>
<?xml-stylesheet type="text/css" href="style.css"?>
The DocBook XSLT stylesheets understand a number of processing instructions to override the default behaviour. [8]
A draft specification for Robots exclusion standard rules inside XML documents uses processing instructions. [9]