I dont like the amount of tags in the head of my document. here is an example of some meta tags.
<!--w3c-->    
<title>Page Title</title>
<meta name="description" content="great description">
<!--schema.org-->
<meta itemprop="name" content="Page Title">
<meta itemprop="description" content="great description">
<!-- opengraph-->
<meta property="og:title" content="Page Title">
<meta property="og:description" content="great description">
Is it possible to combine the tags/properties to reduce the code size without affecting SEO?
for example 
 <title itemprop="name">Page Title</title> 
itemprop attributes can be used anywhere so I'm pretty sure this is fine
but as far as i am aware the property="og:*" attribute must be used with a meta tag.
So is the following markup acceptable? 
<meta name="description" itemprop="description" property="og:description" content="great description">
and how will this affect SEO?
many thanks
HTML+RDFa 1.1 and Microdata extend HTML5’s meta element.
HTML+RDFa 1.1 (W3C Recommendation) defines:
If the RDFa
@propertyattribute is present on themetaelement, neither the@name,@http-equiv, nor@charsetattributes are required and the@contentattribute MUST be specified.
Microdata (W3C Note) defines:
If a
metaelement has anitempropattribute, thename,http-equiv, andcharsetattributes must be omitted, and thecontentattribute must be present.
That means:
- It’s not allowed to use Microdata’s - itempropattribute together with HTML5’s- nameattribute.
- It’s allowed to use RDFa’s - propertyattribute together with HTML5’s- nameattribute:- <meta name="description" property="og:description" content="great description" />- (possibly an issue with having this in the - bodyinstead of the- head)
- It seems to be allowed to use Microdata’s - itempropattribute together with RDFa’s- propertyattribute if HTML5’s- nameattribute is not provided:- <meta itemprop="description" property="og:description" content="great description" />- (but the W3C Nu Html Checker reports an error) 
<!DOCTYPE html>
<html vocab="http://www.w3.org/2011/rdfa-context/rdfa-1.1" lang="en" dir="ltr">
<head>
<!--w3c-->    
<title property="schema:name">Page Title</title>
<meta name="description" content="great description">
<!--schema.org-->
<meta property="schema:name" content="Page Title">
<meta property="schema:description" content="great description">
<!-- opengraph-->
<meta property="og:title" content="Page Title">
<meta property="og:description" content="great description">
<meta property="schema:description og:description" content="great description">
</head>
<body>
</body>
</html>
How much meta data you use is up to you. There are at least 5 standards, some like Google+ or Pinterest will fall back to OpenGraph. I don't think any search engine will penalize you for following industry standards. If your website sells product and you have product listing pages with many products per page you will likely want to use schema.org, all the major English language search engines and Yandex have agreed to support it. If your website is more content focussed, schema.org is a lot less important but supporting OpenGraph plus Twitter Cards and even Rich Pins may be more of a necessity.
This is a good article on the various competing standards and which to use. Many people want all the traffic they can get so support many standards.
来源:https://stackoverflow.com/questions/20401085/is-it-possible-to-use-the-same-meta-tag-for-opengraph-and-schema-org