Report abuse 

<html xmlns="http://www.w3.org/1999/xhtml"
      xmlns:xf="http://www.w3.org/2002/xforms">
    <head>
        <xf:model>
            <xf:instance id="selected-values" xmlns="">
                <instance>
                    <pets/>
                    <favorite/>
                </instance>
            </xf:instance>
            <xf:instance id="pets" xmlns="">
                <root>
                    <item name="Cat" value="cat"/>
                    <item name="Dog" value="dog"/>
                    <item name="Fish" value="fish"/>
                    <item name="Cobra" value="cobra"/>
                </root>
            </xf:instance>
        </xf:model>
    </head>
    <body>
        <xf:select ref="pets" appearance="full">
            <xf:label>Please list all your pets:</xf:label>
            <xf:itemset nodeset="instance('pets')/item">
                <xf:label ref="@name"/>
                <xf:value ref="@value"/>
            </xf:itemset>
        </xf:select>
        <br/>
        <xf:select1 ref="favorite">
            <xf:label>Select your favorite pet:</xf:label>
            <xf:itemset>
                <xf:label/>
                <xf:value/>
            </xf:itemset>
            <xf:itemset nodeset="instance('pets')/item[@value = tokenize(context()/../pets, '\s+')]">
                <xf:label ref="@name"/>
                <xf:value ref="@value"/>
            </xf:itemset>
        </xf:select1>
    </body>
</html>