The XForms Function Library includes the entire XPath 1.0 Core Function Library, including operations on node-sets, strings, numbers and booleans.

Besides these XPath 1.0 functions, the XForms specification defines a set of other required functions. These functions are listed within this section, and all of these functions are available within the Smartsite XForms engine.

The function library of the Smartsite XForms engine also contain several extension functions.

As of Smartsite 7.1, also a selection of XPath 2.0 functions are available.