Unix time starts on January 1st, 1970. That time is called the "unix time epoch".
It seems likely that Google is storing the dates as unix time stamps internally and is therefore unable to handle dates before 1970.
Google does not have enough computing power and indexing/freshening varies
There are over 50 billion pages indexed (Tuesday, 19 February, 2013), Google does not have enough computing power to quickly update all pages/sites that get updated on the internet.
Google prioritizes crawling and updates times vary depending on how much importance/authority they ...
The W3C provides Semantic Web logos. Here are the versions without the W3C logo:
But in my experience, these logos are used to represent the concept, they don’t necessarily signal that structured data is available for that page.
For signaling that RDF is available, W3C’s RDF icons are commonly used. ...
As your test code contains some errors, I removed any unneeded data to make it a minimal example:
<head><title>Google Structured Data Testing Tool: date bug?</title></head>
<div vocab="http://rdf.data-vocabulary.org/#" typeof="Event">
Google’s SDTT is intended for checking if the structured data meets the recommendations/requirements for Google’s search features (like rich results). These search features make use of the vocabulary Schema.org.
The type http://xmlns.com/foaf/0.1/Image is from the vocabulary FOAF. This vocabulary is not used by Google for their search features.
So as far ...
Main differences between Microdata and RDFa
Microdata is still a Working Draft (2012-10-25) merely a Working Group Note (2013-10-29). RDFa is a finished Recommendation (2013-08-22) (first Recommendation back in 2008).
Microdata can be used in HTML(5) only. RDFa is markup-independent ("to express structured data in any markup language") and can already be ...
The error the SDTT reports is only for getting Google’s Article rich result. If you don’t want to get the rich result, you can ignore the error.
For getting Google’s Article rich result, the value for image needs to be either a URL, or an Schema.org ImageObject.
So you can either remove the FOAF Image type, so that you only provide a URL value:
All three syntaxes make it possible to provide hidden structured data:
JSON-LD: The script element is hidden by default.
Microdata and RDFa: You can use link/meta elements (which are hidden by default) in the body + meaningless div/span elements if grouping is needed.
Hiding the markup for breadcrumbs will most likely not affect your SEO, as the hidden ...
First of all, "Unspecified Type" is not a warning. The SDTT simply states that no type is specified.
Why does it do this?
Because you are providing a URL value for a property which expects a Text value:
Values expected to be one of these types
It doesn’t make much sense to say that the name is represented/identified by a URL. If your ...
The meta element can’t have a src attribute, and if it appears in the body, it must have a content attribute.
If the value is a URL, you must use the link element instead of the meta element:
<link property="" href="" />
<span property="logo" value="https://schema.org/"></span>
This is invalid HTML, the span element can’t have a value attribute. And if it could have one, the logo property value would be https://schema.org/, but that’s of course not the logo. You probably meant this:
<link property="logo" href="/index.php/Bilder/Virtualbox.png" />
The rel attribute has two different purposes, which might conflict:
Plain HTML: providing a link type
RDFa: providing a property (just like the property attribute, but with some technical differences)
In both of your snippets, it’s interpreted¹ to be the Schema.org property author, not the link type author.
The best general way to prevent such mix-ups is ...
This is correct as breadcrumbs are no started showing in Google Search results
For anyone using this - may ignore <span class="breadcrumbs pathway"> and use his styling class and rest may only change the domain URL and breadcrumb title.
No using RDFa, microdata, richsnippets, and HTML5 does not help your rankings in search engines. If you use Google rich snippet testing tool they'll actually tell you if a page will potentially appear in search results with rich snippets or not. For example a page using hCard but with a lot of other content on that page google may determine the main ...
Now it’s 2013 and two weeks ago the W3C published HTML+RDFa 1.1: Support for RDFa in HTML4 and HTML5 as Recommendation:
This specification defines rules and guidelines for adapting the RDFa Core 1.1 and RDFa Lite 1.1 specifications for use in HTML5 and XHTML5. The rules defined in this specification not only apply to HTML5 documents in non-XML and XML ...
Unless you try to deceive, there is no reason to assume that it could hurt your ranking. But providing structured data typically has no direct influence on the ranking anyway, so it wouldn’t help either.
If you want to provide a meta-description in addition to og:description, you don’t have to duplicate the description, because RDFa allows to use property ...
Not at all. Google does not using open graph meta tags, neither in Search Snippet/Result nor in Search Ranking.
Ref - Meta Tags That Google Understand
OGP is useful for Social Media, because you can use different title in og:title tag, and different images to get more CTR.
As far as I know it wouldn't have any effect on the search rankings, the main purpose of the open graph tags is to make it prettier if the page is shared on social media.
Hope this helps.
If you are using PHP, you could always do the following so you end up with the same description for the meta description tag and the og:description tag:
There are two perspectives:
What is valid RDFa?
What do consumers (like Facebook) support?
The first one can easily be answered by checking the specifications.
The second one depends on each consumer: Is their documentation up-to-date/accurate/complete? How good are their parsers?
For consumers, it would make absolutely no sense to support only a ...
MedicalSignOrSymptom is for adding markup to the sign or symptom itself, therefore the name property is the sign or symptom, i.e.:
<div vocab="http://schema.org/" typeof="MedicalSignOrSymptom">
<p>Patient complains of <span property="name">severe abdominal pain</span>.</p>
It’s valid to use RDFa in HTML5.
While xmlns still works, it is deprecated in HTML+RDFa 1.1. You should use the prefix attribute instead. If only one vocabulary is used, you could also use the vocab attribute instead of prefix.
RDFa is much more powerful than Microdata. RDFa Lite (a subset of RDFa), however, is very similar to Microdata.
Here is a small ...
(I adjusted my answer that I gave to your (now closed) question on SO.)
When a user-agent (including search engines) parses your RDFa, it doesn’t matter which element the RDFa is used on (except for special parsing rules). The user-agents learns something like the following:
There is a business entity (http://purl.org/goodrelations/v1#BusinessEntity) ...