[uf-discuss] dfn design pattern (proposal)

Jeremy Keith jeremy at adactio.com
Fri Aug 17 04:44:27 PDT 2007

This is may be somewhat premature as the results of the assistive  
technology tests aren't back yet:

But if we do need to look at alternatives to the abbr design pattern,  
one of the ideas that came up in discussion was to use the dfn element.

I've put together a page on the wiki outlining the thinking behind  
this proposal as well as highlighting some of the potential downsides:


On the plus side, I think it's better not to widen the title design  
pattern to apply to any element (which is essentially what the span  
proposal is saying) so this would only be a slight expansion.

On the down side, the semantics of "defining instance" aren't always  
going to be applicable for datetime, geo, etc. But I think it could  
well cover 80% of use cases.

What's needed:

* Arguments for or against the use of dfn as a container for the  
title design pattern: is this semantic abuse or is it simply  
stretching semantics (like the abbr design pattern).

* Document usage of the dfn element in the wild: I believe it is  
often used in conjunction with the title attribute.

* Test results from screen readers to find out if dfn is treated as a  
special case (like abbr and acronym) or whether it is "safe" to use.

* Feedback from the people building parsers (Mike Kaply, Brian Suda,  
etc.) on whether this would be tricky or easy to implement.

I'm fairly certain that this proposed design pattern would *not*  
cover 100% of use cases but it might cover enough situations to be  
viable as *an alternative* to the abbr design pattern.

Note that I am not suggesting that the abbr deisgn pattern should be  
deprecated. I believe it has its place but I think it would be good  
to provide an alternative to address the accessibility question.

For instance, even if the dfn design pattern is adopted, I will still  
use the abbr element for cases like this:

<abbr class="dtstart" title="2007-08-19">August 19th</abbr>

That's because I believe exposing the string "2007-08-19" either to  
sighted or blind users is an acceptable, readable, understandable way  
of formating a date. But for a string like "2007-08-19T12:39:00" I  
would like to have an alternative that wouldn't directly expose that  
format to the user.

That's my own call, of course. I suspect that others, offered the  
choice of an alternative to abbr, will always go for the alternative.  
And others will choose to always stick with abbr. I think that all of  
those positions should be accommodated.

Look forward to getting your feedback,



Jeremy Keith

a d a c t i o


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