Thank you for this work. I agree that this is useful and worth doing, but have some questions about the implementation.

I am a bit concerned about using a hard-coded value, would in be better to allow this to be threaded throughfig.savefig(...) with a default of'svg1'? Would a less generic string (likematplotlib ormpl) be better as a default?

I share the concern of a hard-coded value.

Configuration can be

• either viasavefig() - T.b.d. how to fit this in the signature. A top-levelid parameter is a bit awkward, because it would only be used for the SVG renderer. Alternatives would be a genericrederer_params dict, or (a bit hacky) put it inmetadata and let the SVG renderer pop it from there.
• or if threading throughsafefig is too much song and dance API-wise, just create an rcParam. This would be a little more cumbersome to use but simpler to implement. - Ok if setting id is really rare.

I also believe, the default should be no attribute, as it is now. Setting the attribute should be opt-in.

Fair enough, I went the hardcoded route because there was indeed no straightforward path to pass it throughplt.savefig().
I think myuse-case is fairly niche, and it shouldbecome irrelevant when SVG2.0 is adopted (which may be never though).

If you agree on an approach I'd be happy to draft an implementation!

If the application is fairly niche, I'd go with an rcParamsvg.id (default: None); seehere:

I also support going the rcparam route with default behavior beingNone as Tim proposes.

I've added an implementation using rcparams.

Thanks@willemsk and congratulations on your first contribution to Matplotlib! We'd welcome to see you back.