ins and del elementsThe cite attribute
  may be used to specify the address of a document that explains the
  change. When that document is long, for instance the minutes of a
  meeting, authors are encouraged to include a fragment identifier
  pointing to the specific part of that document that discusses the
  change.
If the cite attribute is
  present, it must be a valid URL potentially surrounded by
  spaces that explains the change. To obtain
  the corresponding citation link, the value of the attribute must be
  resolved relative to the
  element. User agents should allow users to follow such citation
  links.
The datetime
  attribute may be used to specify the time and date of the change.
If present, the datetime
  attribute's value must be a valid date string with optional
  time.
User agents must parse the datetime attribute according to the
  parse a date or time string algorithm. If that doesn't
  return a date or a global date and time, then the
  modification has no associated timestamp (the value is
  non-conforming; it is not a valid date string with optional
  time). Otherwise, the modification is marked as having been
  made at the given date or global date and time. If the given
  value is a global date and
  time then user agents should use the associated time-zone
  offset information to determine which time zone to present the given
  datetime in.
The ins and del elements must implement the HTMLModElement
  interface:
interface HTMLModElement : HTMLElement {
           attribute DOMString cite;
           attribute DOMString dateTime;
};