From http://www.w3schools.com (Copyright Refsnes Data)
XQuery 1.0, XPath 2.0, and XSLT 2.0 share the same functions library.
XSLT includes over 100 built-in functions. There are functions for string values, numeric values, date and time comparison, node and QName manipulation, sequence manipulation, Boolean values, and more.
The URI of the XSLT function namespace is:
http://www.w3.org/2005/02/xpath-functions
The default prefix for the function namespace is fn:.
Tip: Functions are often called with the fn: prefix, such as fn:string(). However, since fn: is the default prefix of the namespace, the function names do not need to be prefixed when called.
The reference of all the built-in XSLT 2.0 functions is located in our XPath tutorial.
In addition, there are the following built-in XSLT functions:
| Name | Description |
| current() | Returns the current node |
| document() | Used to access the nodes in an external XML document |
| element-available() | Tests whether the element specified is supported by the XSLT processor |
| format-number() | Converts a number into a string |
| function-available() | Tests whether the function specified is supported by the XSLT processor |
| generate-id() | Returns a string value that uniquely identifies a specified node |
| key() | Returns a node-set using the index specified by an <xsl:key> element |
| system-property() | Returns the value of the system properties |
| unparsed-entity-uri() | Returns the URI of an unparsed entity |
From http://www.w3schools.com (Copyright Refsnes Data)