Create a filter
XSLfast offers additional means to navigate through an XML structure and address desired nodes or to add conditions to the structure. This is achieved by filters, which can also be called virtual groupings or virtual nodes. You create filters if you want to have certain effects, which cannot be achieved with the existing groupings, like a sorted display of node contents, additional information under certain conditions. You need XSL skills to use the possibilities of virtual groupings to the full extent.