Why are svg tagNames lowercase and non-svg uppercase?-CodePudding

Why is one lowercase and the other uppercase ?

console.log("standard :", document.getElementById('link').tagName)  // A

console.log("svg : ", document.getElementById('SvgLink').tagName)  // a

<svg xmlns="http://www.w3.org/2000/svg" width="100" height="100" viewBox="0 0 100 100" style="background: peachpuff;">
    <a id="SvgLink" href="http://perdu.com">
        <circle  cx="50" cy="50" r="40" stroke="black" stroke-width="3" fill="red"></circle>
    </a>
</svg>

<a id="link" href="http://perdu.com">Link</a>

CodePudding user response：

SVG's original format was XML only. XML is case sensitive. Some of that case sensitivity remains for compatibility reasons when SVG is embedded within HTML documents.

See DOM level 2 core description of tagName

...Note that this is case-preserving in XML, as are all of the operations of the DOM...