If not empty, this allows you to format the value of this field using HTML, allowing you to do things like link or mark up the output. You may use these placeholders: <b>{$value}</b> - the field's display value; <b>{$valueUrl}</b> - the field's display value for use in a URL, <b>{$choice}</b> - the underlying value of the chosen option, and <b>{$fieldId}</b> - the ID of this field (<span id="FieldId">{fieldId}</span>).