Datatypes |
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XPath and XSLT define five datatypes, listed here. The result tree fragment type is defined by XSLT and is specific to transformations; the other four are defined by XPath and are generic to any technology that uses XPath. The four XPath datatypes are tersely defined in Section 1 of the XPath specification; section 11.1 of the XSLT specification defines result tree fragments.
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node-set
-
A set of nodes. The set can be empty, or it can contain any number of nodes.
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boolean
-
The value
true
or
false
. Be aware that the strings
true
and
false
have no special meaning or value in XPath. If you need to use the boolean values themselves, use the functions
true()
and
false()
.
-
number
-
A floating-point number. All numbers in XPath and XSLT are implemented as floating-point numbers; the
integer
or
int
datatype does not exist in XPath and XSLT. To be specific, all numbers are implemented as IEEE 754 floating-point numbers, the same standard used by the Java
float
and
double
primitive types. In addition to ordinary numbers, there are five special values for numbers: positive and negative infinity, positive and negative zero, and
NaN
, the special symbol for anything that is not a number.
-
string
-
Zero or more characters, as defined in the XML specification.
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result tree fragment
-
A temporary tree. You can create one with an
<
xsl:variable
>
element that uses content (instead of the
select
attribute) to initialize its value. A result tree fragment can be copied to the result tree with the
<
xsl:copy-of
>
element. It may also be converted to a string with the
<
xsl:value-of
>
element.
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