<abbr class="foo" title="YYYY-MM-DDTHH:MM:SS+ZZ:ZZ">Date Time</abbr>
I think this is a misuse of the abbreviation tag - and worse: it’s completely ignoring user experience. Most of nowadays browsers display the text of the title attribute when you hover over the abbreviation. Now imaging a user browsing your microformatted page. When he hovers over a date like - say - May 4th 1970, which is my birthday, he’ll see a tooltip stating “1970-05-04T18:10:52+01:00”. Doh!
Not to tell that screen readers usually read the abbreviation’s title. So, a screen reader would read “One Nine Seven Zero Minus Zero Five Minus Zero Four T One Eight Colon…” Really well done, you microformat people.
The point of including expanded forms of abbreviations is to make sure that users can access those forms if needed. The value of the abbr element lies in its ability to tell screen readers what they should read (thus improving the flow of spoken text), while also providing additional useful information to visual users with learning or cognitive disabilities (or those coping with language barriers). The assertion that abbr is structural is misguided, as the point of the tag is the content of its title attribute.
He’s right. Abbreviation is not structural. Even it it once was intended to be, in real life it isn’t. It seems, this has been forgotten by the microformat astronauts.