You can't necessarily say "We 8:00-2:00" because your closing hour could be after your opening hour on the next day and it would be ambiguous. E.g. Opening at 2am and closing the next day at 4am. I know that's absurd for most libraries but it may happen. A better example is when a library stays open overnight just one day a week. 

Ideally, if working with times with date granularity you should honor that choice and say "We 8:00-24:00" and "Th 0:00-2:00". Then, when creating human readable formats you always check tomorrow in the event today's closing time is midnight.

Brice
—
Sent from my iPhone

On Jun 8, 2011, at 1:00 PM, "Nate Vack" <[log in to unmask]> wrote:

> On Wed, Jun 8, 2011 at 11:45 AM, Kevin S. Clarke <[log in to unmask]> wrote:
> 
>> <time itemprop="openingHours" datetime="Mo,We,Fri 17:00-21:00">Mondays, Wednesdays, and Fridays 5-9pm</time>
> 
> Or, if you just want to talk about
> http://library.example.com/hours/today, (which I think is what the OP
> was about?) you could do:
> 
> <time itemprop="openingHours" datetime="We 8:00-21:00">Open today
> (Wednesday, June 8) from 8:00 am to 5:00 pm</time>
> 
> Note that if you're open from, say, 8:00 AM to 2:00 AM, it raises some
> interesting discussions about what exactly goes in those time ranges,
> and when "today" should change. I'd vote datetime="We 8:00-2:00" and
> changing "today" shortly after 2am, but there are valid arguments that
> that's a dumb vote.
> 
> The easy solution: change policy to never be open past midnight ;-)
> 
> Cheers,
> -Nate