XML CDATA
All text in an XML document will be parsed
by the parser.
But text inside a CDATA section will be ignored by the parser.
PCDATA - Parsed Character Data
XML parsers normally parse all the text in an XML document.
When an XML element is parsed, the text between the XML
tags is also parsed:
<message>This text is also parsed</message>
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The parser does this because XML elements can contain other elements,
as in this example, where the <name> element contains two other elements (first
and last):
<name><first>Bill</first><last>Gates</last></name>
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and the parser will break it up into sub-elements like this:
<name>
<first>Bill</first>
<last>Gates</last>
</name>
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Parsed Character Data (PCDATA) is a term used about text data that will be
parsed by the XML parser.
CDATA - (Unparsed) Character Data
The term CDATA is used about text data that should not be parsed by the XML
parser.
Characters like "<" and "&" are illegal in XML elements.
"<"
will generate an error because the parser interprets it as the
start of a new element.
"&"
will generate an error because the parser interprets it as the
start of an character entity.
Some text, like JavaScript code, contains a lot of "<" or "&"
characters. To avoid errors script code can be defined as
CDATA.
Everything inside a CDATA section is ignored by the parser.
A CDATA section starts with "<![CDATA[" and ends with
"]]>":
<script>
<![CDATA[
function matchwo(a,b)
{
if (a < b && a < 0) then
{
return 1;
}
else
{
return 0;
}
}
]]>
</script>
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In the example above, everything inside the CDATA section is ignored by
the parser.
Notes on CDATA sections:
A CDATA section cannot contain the string "]]>". Nested CDATA
sections are not allowed.
The "]]>" that marks the end of the CDATA section cannot contain spaces or line breaks.
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