upload-relevant.xml

<?xml version="1.0"?>
<h:html xmlns="http://www.w3.org/2002/xforms" 
    xmlns:ev="http://www.w3.org/2001/xml-events" 
    xmlns:h="http://www.w3.org/1999/xhtml" 
    xmlns:jr="http://openrosa.org/javarosa" 
    xmlns:odk="http://www.opendatakit.org/xforms" 
    xmlns:orx="http://openrosa.org/xforms" 
    xmlns:xsd="http://www.w3.org/2001/XMLSchema">
    <h:head>
        <h:title>file-readonly-relevant</h:title>
        <model>
            <instance>
                <file-readonly-relevant id="file-readonly-relevant">
                    <a/>
                    <img1/>
                    <img2/>
                    <meta>
                        <instanceID/>
                    </meta>
                </file-readonly-relevant>
            </instance>
            <bind nodeset="/file-readonly-relevant/a" type="int"/>
            <bind nodeset="/file-readonly-relevant/img1" readonly="true()" type="binary"/>
            <bind nodeset="/file-readonly-relevant/img2" readonly="true()" relevant=" /file-readonly-relevant/a > 3" type="binary"/>
            <bind calculate="concat('uuid:', uuid())" nodeset="/file-readonly-relevant/meta/instanceID" readonly="true()" type="string"/>
        </model>
    </h:head>
    <h:body>
        <input ref="/file-readonly-relevant/a">
            <label>Enter number &gt; 3 to make relevant</label>
        </input>
        <upload mediatype="image/*" ref="/file-readonly-relevant/img1">
            <label>Upload</label>
        </upload>
        <upload mediatype="image/*" ref="/file-readonly-relevant/img2">
            <label>Upload with relevancy expression</label>
        </upload>
    </h:body>
</h:html>