"<defs>"

Container for definitions of reusable graphics elements.

It is not rendered directly, but its child elements can be referenced by a "<use>" or within a fill or stroke.

• DOM object: SVGDefsElement
• SVG2 spec: https://www.w3.org/TR/SVG2/struct.html#DefsElement

<defs>
 <linearGradient id="MyGradient"><!-- ... --></linearGradient>
</defs>