The Road Ahead - HTML5 Mastery: Semantics, Standards, and Styling - page 341

cached
FALLBACK:
images/logo.png images/offline-logo.png
contact.php contact.html
This would need to appear on any page that was using the cache. The files listed
under the CACHE section will be stored on the client machine and retrieved as necessary
to navigate the site. Any files appearing under the NETWORK section will always be
fetched from the server. The FALLBACK section maps pairs of files together so that if
the first one is not found, the second one will take its place on a page. Using fallbacks,
you can provide visual clues to the user that they are surfing a cached version of the
page. For example, you could provide alternate images that are branded “offline,” which
would show up only when the user was viewing the cached images.
Other HTML5 technologies
There are a number of technologies in the HTML5 family that either are not mature
enough or are too broad to address within the scope of this topic. However, that is no
reason you shouldn't be aware of their existence! What follows is a high-level overview
of these technologies.
Microdata
Microdata is HTML5 for machines. It's for search engines and other external applica-
tions that may want to derive meaning from your content but need more information to
understand it. To do this, existing HTML elements can be annotated with attributes that
define the type of data on the page to a much finer degree than what is possible with
existing semantic HTML elements.
At its most basic level, Microdata uses three attributes: itemscope , itemtype ,
and itemprop . Consider, for instance, a paragraph about this topic:
<p>
HTML5 Mastery: Semantics, Standards, and Styling by Anselm
Bradford and Paul Haine.
</p>
To mark this up using Microdata, first the itemscope property is added to indicate
that this paragraph contains a collection of data that is related, a book and authors in this
case: