{%- call
  form.checkbox('fields__' ~ position ~ '__tdimmutable',
    label=_('Immutable'),
    id='field-f' ~ position ~ 'immutable',
    checked=data.get('tdimmutable', field.get('tdimmutable', '')),
    error=errors.tdimmutable,
    value='true'
  )
  -%}
  {{ form.info(
    text=_('The value may be set once then not changed afterwards')
  )}}
{%- endcall %}
