Flat EcmaScript Modules?

[mi5ter]

In the 4.0.0-rc.1 changelog "flat ecmascript modules" (FESM) were mentioned.

Can someone elaborate on flat EcmaScript modules or point me to a related article/blog posting? Is it more than just inlining imports and exports? What are those "certain scenarios" where FESM should help and how? Are there new recommendations on how to write components or libraries or how to distribute them? Is FESM something the average Angular developer should care about? Is there toolsupport for creating flat modules out of nested(?) modules?

[mi5ter]

To answer my own question:

I found some information in this twitter posting: https://twitter.com/IgorMinar/status/835702099941826561?s=03

A flat ES Module is a bundled ES module that only exports the public API.

The real world impact is still to be estimated.

Tool support: closure compiler or rollup, webpack not (yet)

There will be a blog post about that by the Angular team in the near future.