So you don't have to add Microdata manually.
The markup of Microdata consists of 3 elements: itemscope, itemtype and itemprops.
I think its a shame google have opted for Microdata rather than microformats.
Org Microdata implementation has been all the rage of late,
the execution hasn't, apparently.
The move to Microdata and the changes to WordPress required a new article: this is it!
Microdata Library, providing data on people living in developing countries,
their institutions, their environment, their communities and the operation of their economies.
According to the results, 29 percent of websites are dealing with duplicate content, and furthermore,
a whopping 80 percent of websites aren't currently using Microdata.
On this website, an initiative of the three biggest search engines(Google, Bing and Yahoo),
you will find a shared collection of schemas(Microdata) that you can use.
I believe bing are backing Microdata too, so presumably that means yahoo as well,
which makes for pretty much the entire English language search engine market.
Microdata was lower overhead in a way because it doesn't
require any new properties- its economical to use classes as you can also apply styles to them.
I'm in no way saying that Microdata is the best option(there are advantages and disadvantages to
every type mentioned) but for me, Microdata offers the most advantages.
Microdata is also recommended by Google,
so for people who like to follow Google's guidelines, this can be a reason to choose Microdata over microformats and RFDa.
Additionally, with the recent indications that Microdata may play a factor in determining rankings,
we would expect to see this number jump in the next set of survey results.
On the other hand, Microdata is less confusing for precisely the same reason-
if there is an itemprop or itemtype or itemscope you know its for Microdata and if there is a class you know its for styling.
So, each of your product pages is correctly structured using Google's SEO-friendly format(also known as Microdata), which allows search engines to create
rich snippets(these are pieces of copy that appear in search results which help entice readers to click through to your site).
This prevents google recognising the Microdata and avoids the problem of having more than 1 type,
but means that when google do switch all you have to do is re-add the itemtype and itemscope and all the rest of the Microdata will show up.
According to census Microdata crunched by the University of Minnesota's IPUMS, the mean age for marriage for women born
between 1821 and 1830(Virginia was born in 1822) was 22.6 years, and among those who ever got married(which was over 90% of the female population in those days), only 12.6% were married by the time they were 19.