Option 1:

  <meta name="date.created" content="YYYY-MM-DD"> (authored date)
  <meta name="date.available" content="YYYY-MM-DD"> (published date)
  <meta name="date.updated" content="YYYY-MM-DD; YYYY-MM-DD"> (date or dates that CONTENT was changed/updated)
  <meta name="date.modified" content="YYYY-MM-DD; YYYY-MM-DD"> (date or dates that HTML page was modified
                                                               in any way; e.g. html coding, encoding, styles,
                                                               or formatting changed,
                                                               but _content_ was not significantly changed.
                                                               May share the same date as 'date.updated' if both
                                                               content and formatting were changed at the same time.)
link: http://www.schemas-forum.org/registry/desire/element.php3?field=ID&value=dcq/date/modified
  ["CONTENT", in parenthetical definitions above (_not_ in meta code) indicates words, sentences, images, 
     video, audio, or any other human communication format]<meta name="author" content="Author Name"> (content author. If this is the only 'author' tag, it should be assumed a single person
                                                                     wrote the content, created the style of the page, and published the page)
  <meta name="format_author" content="Author Name"> = "Web Author". 
                                       The person or persons who "html'ized" the document, only needed if
                                       a different person than the content author developed the document for web delivery.
  <meta name="format_designer" content="Author Name"> = Site Designer. 
                                     The person or persons (if different than persons above) who designed the style used on the page)

Option 2:

  <meta name="content_origin"  content="2005-04-02">
  <meta name="content_updated" content="2005-04-02">
  <meta name="minor_updates"   

Option 3:

Abandon illogical, coder-designed HTML model.
Use logical, human readable, externally defined tags.
Design computer systems and applications with enough intelligence
to parse and process variations created by humans.
(As opposed to trying to program humans to create code readable by computer systems.)


<meta> <meta-terms-defined-at>http://example.com/meta_defintions/</meta-terms-defined-at>
<date-updated>YYYY-MM-DD; YYYY-MM-DD</date-updated>
<date-modified>YYYY-MM-DD; YYYY-MM-DD; YYYY-MM-DD</date-modified>