...
<field id="measurementUnit">
<options>
<option id="" default="yes">Please select >Select a value<unit</option>
<option id="carats">Carats<>carats</option>
<option id="centimeters">Centimeters<>centimeters</option>
<option id="cubic_centimeters">Cubic Centimeters<>cubic centimeters</option>
<option id="feet">Feet<>feet</option>
<option id="grams">grams</option>
<option id="inches">Inches<>inches</option>
<option id="kilograms">Kilograms<>kilograms</option>
<option id="liters">Liters<>liters</option>
<option id="millimeters">Millimeters<>millimeters</option>
<option id="meters">Meters<>meters</option>
<option id="minutes">Minutes<>minutes</option>
<option id="pixels">Pixels<">pixels</option>
<option id="pounds">pounds</option>
<option id="square_feet">Square Feet<>square feet</option>
<option id="square_inches">square inches</option>
<option id="storiesyards">Stories<>yards</option>
</options>
</field>
...