+ /**
+ * Controls use of 'extra' field
+ *
+ * Extra field can be used to add link to form, which allows
+ * to modify all fields supported by backend. This is the only field
+ * that is not sanitized with htmlspecialchars. Backends MUST make
+ * sure that field data is sanitized and displayed correctly inside
+ * table cell. Use of html formating in other address book fields is
+ * not allowed. Backends that don't return 'extra' row in address book
+ * data should not modify this object property.
+ * @var boolean
+ * @since 1.5.1
+ */
+ var $add_extra_field = false;