[ska]

That's really not how it works. The FDA is fundamentally concerned about two things, safety and efficacy. You need a plan to demonstrate the latter, and you need your quality system, SDP, etc. to demonstrate how you approach the former. This is about good engineering practices, not particular implementation techniques.

So you can do things many different ways. If you do say "we do this like X, which is industry standard, just like T, U, and V do" it's a simpler argument than "we do this like Y. Lots of people do X, but here is how we have demonstrated Y is better for us...". But this can be fine too, just possibly more work.

Also worth noting (a) there is no industry-wide best practices agreement (b) there is no FDA wide agreement on what should be done (different device types are reviewed by different panels (c) the FDA doesn't understand software development deeply across it's panels, but it is catching up.

[AnimalMuppet]

Sure, that's all true. I'm looking at the "simpler argument" part.

It's especially true if you're saying "This new device is just like our previous device, with these few small changes". (I forget what that's called, but you can do a lot less paperwork if that's true.) But if you start doing memory allocations where you never did before, they're probably going to want to apply higher scrutiny to your entire software. That's... painful.

[ska]

You are possibly thinking about note-to-file (which isn’t quite the process any more, but similar)

But it is worth pointing out, FDA (or other national body) isn’t doing code reviews. They are mostly interested in process , and how you follow it. The place where this really interacts s is hazard analysis, and then it’s just up to you to demonstrate your checks and balances.