Why this MathJax SVG in an image data URI does not work?

Question

<img src='data:image/svg+xml;base64,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' />

Here's a sample fiddle: http://jsfiddle.net/elhoyos/KL489/

I took the liberty to include the deps glyphs MathJax provides in another SVG element of the same document.

Answer 1

When you embed SVG within html namespaces are optional when you reference a file where the svg node is the root then they are not.

You are missing the SVG namespace in your encoded data i.e. you need

xmlns="http://www.w3.org/2000/svg"

on the root node.

Your example works for me with that change.