--- /dev/null
+/**
+ * Implements hook_field_attach_form().
+ */
+function {{ machine_name }}_field_attach_form($entity_type, $entity, &$form, &$form_state, $langcode) {
+ // Add a checkbox allowing a given field to be emptied.
+ // See hook_field_attach_submit() for the corresponding processing code.
+ $form['empty_field_foo'] = array(
+ '#type' => 'checkbox',
+ '#title' => t("Empty the 'field_foo' field"),
+ );
+}