EXSLT is a community initiative to provide extensions to XSLT. The extensions
are broken down into a number of modules, listed below. Implementers of XSLT
processors are encouraged to use these extensions, so that your stylesheets can
be more portable. If your XSLT processor doesn't support a particular
extension, you will find packages that you can use to provide functions or
templates for your stylesheets.

- Common: common, basic extension elements and functions.
- Math: facilities to do with maths.
- Sets: facilities to do with set manipulation.
- Functions: allow users to define their own functions for use in expressions
  and patterns in XSLT.
- Dates and Times: date and time-related extension elements and functions.
- Strings: facilities to do with string manipulation.
- Regular Expressions: facilities to do with regular expressions.
- Dynamic: dynamic evaluation of strings containing XPath expressions.
- Random: facilities to do with randomness.

WWW: http://www.exslt.org/