The XML returned from direct REST calls to Connections 4.0 returns dates like so, from a File:
<published>2013-08-06T15:00:08.390Z</published>
<updated>2013-08-15T15:30:20.367Z</updated>
<td:created>2013-08-06T15:00:08.390Z</td:created>
<td:modified>2013-08-15T13:16:59.151Z</td:modified>
<td:lastAccessed></td:lastAccessed>
and from a File Comment:
<published>2013-08-08T18:04:44.949Z</published>
<updated>2013-08-08T18:05:39.566Z</updated>
<td:modified xmlns:td="urn:ibm.com/td">2013-08-08T18:05:39.566Z</td:modified>
<td:created xmlns:td="urn:ibm.com/td">2013-08-08T18:04:44.949Z</td:created>
The API documentation is vague about the conditions under which these dates are set:
<td:created> Creation timestamp in Atom format. <td:modified> The date that the comment was last updated. Timestamp in Atom format. <updated> The date that the comment was last updated, as defined in the Atom specification. <published> The date the comment was initially published, as defined in the Atom specification.
Can one assume that <published> == <td:created> and that <updated> == <td:modified>, as the data seems to indicate, or are there circumstances under which these dates would have different values? Does the answer to this question vary by application (Files, Blogs, etc.)?
<updated> and <published> are Atom-defined properties. The <td:...> ones are IBM's extensions.
Another way to ask my question might be, What descriptions or definitions would I use to explain each of these dates to a user?
Whilst td:created and published are generally identical, with the foremost exception of content created as a draft and later published, applications use td:modified and updated with slightly different semantics. In Wikis for instance updated reflects the time page contents or metadata last changed, while td:modified is only updated when page contents i.e. title or text are updated. I expect the API documentation to clarify these subtle details, if not please post comments and ask for improvements.