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The only permitted value for the xmlns:link attribute is http://www.w3.org/1999/xlink.
Although using https in the URL looks like it’s going to be more secure, in fact this URL is not used to connect it to, only to declare the namespace.
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Related W3C validator issues
The only permitted value for the xmlns attribute is http://www.w3.org/2000/svg.
The namespace declaration for an <svg> element is provided by the xmlns attribute like this:
<svg xmlns="http://www.w3.org/2000/svg">
<!-- more tags here -->
</svg>Although using https in the URL looks like it’s going to be more secure, in fact this URL is not used to connect it to, only to declare the namespace.
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