joomla/com_wk1_6/admin/models/forms/wk1.xml

<?xml version="1.0" encoding="utf-8"?>
<form                addrulepath="/administrator/components/com_wk1/models/rules">
    <fieldset>
        <field
                name="id"
                type="hidden"
                />
        <field
                name="greeting"
                type="text"
                label="COM_WK1_WK1_GREETING_LABEL"
                description="COM_WK1_WK1_GREETING_DESC"
                size="40"
                class="inputbox"
                validate="greeting"
                required="true"
                default=""
                />
    </fieldset>
</form>