freesewing/markdown/dev/reference/api/svg/defs/en.md

title
defs

A string that will be rendered as the defs section of the SVG document.

The defs attribute is where plugins will add additional snippets.

<defs>
  /* svg.defs will be inserted */
</defs>

Add, but don't overwrite

When adding your own defs, it's important not to overwrite this property, but rather add your own.

In other words, do this:

svg.defs += myDefs;

and don't do this:

svg.defs = myDefs;