Google, yahoo have some new norm for "Copy contents"

According to Google's blog for webmasters reported that Google, Yahoo, Microsoft will support a new standard that allows website administrators to remove the copy from their own website content, which will make the search results more comprehensive and standardized.
The so-called duplicate content refers to the refers to the same domain name or a large segment between the cross-domain content exactly the same as or very similar. For example, Discuz forum posts have another print edition, or mobile phone version, so a different URL addresses produced almost identical content. Reproduced between the different sites is also another type of copy the content. Through a new specification that enables search engines know the content of the smooth preferred version.
The specific approach is to copy the content in the area of the page to increase a line similar to:
Now, you just add this tag to specify your preferred version:

The link inside the link as the preferred address, so, Google will be able to quickly copy the contents of the exclusion, while the focus on improving the ranking of the preferred link address.
According to Google introduced the mark completely different domain name for a copy of the content inside does not work for different domain names, Google recommends the use of 301 redirects to reduce copy the content.