Definition(en): ZFO file is a ZIP archive file containing the FO electronic form. The FO electronic form is a XML data file containing an electronic form intended for usage in the 602XML applications. The form is a composure of the layout structure using XSL-FO, data instance and data model using generic XML elements defined in the 602XML framework. The whole electronic form structure is always embedded into a digital signature represented by XML elements of the XML Signature standard. ZFO file can be password protected.