
                                        <xxf:variable select="normalize-space(string-join((year, month, day), ''))" name="c" as="xs:string"></xxf:variable>
                                        <xf:action if="$c = ''">
                                            <xf:setvalue ref="is-valid" value="false()"></xf:setvalue>
                                            <xf:setvalue ref="$binding"></xf:setvalue>
                                        </xf:action>
                                        <xf:act