Supersedes Three Dates for Atom, 14 Mar 2004.  Supersedes Three Dates for Atom, 14 Jul 2004.

Dates for Atom Entries

Volume 7, Issue 122; 14 Jul 2004; last modified 08 Oct 2010

My new thinking is that Atom only needs to provide two dates: issued and modified. Revisions can better be handled by constructing a version chain.

The “three dates” model provides created, issued, and modified dates.

What bothers me most about reissuing an essay is that the new content replaces the old. On the one or two occasions when I’ve done this, I’ve struggled to preserve the original essay somewhere in the revised essay so that readers could see both what I originally said and what I’m saying now.

Somewhere in the long discussion of dates on the Atom syntax mailing list, I became convinced that we could simplify the whole thing by just having two dates: issued and modified.

Issued is when the essay was published. Publication happens once and history is never revised. Small changes, fixing links or typos, updates the modified date, but the original content is never changed in significant ways. (This is a partly social contract, of course, there’s nothing that can prevent me from completely changing an essay without updating either date.)

Then the question is, what happens when someone wants to change an essay in some significant way? The right answer, I now think, is to publish a new essay and use metadata to indicate that it replaces the old one. The DCMI Metadata Terms, particularly replaces and isReplacedBy seem ideally suited to this purpose.

This essay demonstrates how that might work. (It supersedes Three Dates for Atom .)

Further discussion on the list leads me to think that I haven’t actually contributed to consensus. C’est la vie. At the very least, I was spurred to implement the idea on this site.


There's still a role for created in this model. It's the time when the content was originally written. As opposed to issued which sais when the content was published at the indicated location.

Btw, the 3 links to the dublin core site are broken.

—Posted by Sjoerd Visscher on 14 Jul 2004 @ 02:54 UTC #

The links are only broken on the talkback page. Actually, all links in the article are broken on the talkback page.

Also I forgot to say that I completely agree with you, just that created can still be used too.

—Posted by Sjoerd Visscher on 14 Jul 2004 @ 03:02 UTC #

I knew you would come around ;)

—Posted by Robert Sayre on 14 Jul 2004 @ 10:16 UTC #

Perhaps has-version and is-version-of are the correct candidates (rather than replaces/is-replaced-by)?

—Posted by Chris Purcell on 15 Jul 2004 @ 03:16 UTC #