Information is passed on the calls between the different templates. This information is bundled in so called node sets. The signature of the different node sets is described in Appendix C.
Along with the node sets a 'custom' parameter is passed on between the templates. The navigation layer will only pass this parameter on, and not interpret it. The parameter can be used to distinguish between different traversals of the XForms structure, if that is required as part of the customization. The Example below illustrates the intended use of the 'custom' parameter.