{%- call
  form.input('fields__' ~ position ~ '__tdpattern',
    label=_('Pattern'),
    id='field-f' ~ position ~ 'pattern',
    value=data.get('tdpattern', field.get('tdpattern', '')),
    error=errors.tdpattern,
    classes=['control-full']
  )
  -%}
  {{ form.info(
    text=_('Regular expression to match against the field, e.g. '
    '<code>AB-\\d{6}</code> for text starting with <code>AB-</code> '
    'and ending with 6 digits')
  )}}
{%- endcall %}
