form.xml

<?xml version="1.0" encoding="UTF-8"?>
<form>
    <fields name="main">
        <fieldset name="langroot-set">
            <field
                    type="text"
                    name="langroot-text"
                    id="langroot-text-id"
                    label="Langroot text field label"
                    description="I describe everything"
                    size="80"
                    maxLength="255" />
        </fieldset>
    </fields>
</form>