s="node()?">
                                <xxf:sequence xxbl:scope="outer" select="."></xxf:sequence>
                            </xxf:variable>
                            <xxf:variable select="$binding/string()" name="value" as="xs:string">
                                <xf:action if="$binding castable as xs:positiveInteger" ev:event="xforms-value-changed xforms-enabled">
                                    <xf:setvalue ref="instance('number-instance')/area" value="substring($binding, 1, 3)"></xf:se