• XPath has a set of standard functions that can be used in XPath expressions
• If they have arguments, these are separated by commas
• Their main use is in predicates

Test whether the substring in the current element's content, starting at character #5 and having two characters, can be converted to the number 25:

   <xsl:if test="number(substring(.,5,2)) = 25">

• The 25 XPath function are extended by XSLT 1.0 to make 36 in total
  • conversions (eg, number())
  • string manipulation (eg, concat())
  • arithmetic (eg, floor(), sum())
  • getting node and identifier names (eg, lang())
  • boolean (eg, not())
  • context information (eg, last())
• Some were described last week. Implementations can extend the basic set of functions such as Saxon and MSXSL functions to convert Result Tree Fragments back into Nodesets.