What are states and how are they set up?

[Ferriq]

I noticed the SetStates in the documentation, and at a guess they define subsections of an animation to play.

But how are they defined?

In animation creators like LottieLabs or LottieFiles, custom animation states can be defined, but it looks like this is there own proprietary implementation which wouldn't work when exported as normal Lottie JSONs.

Any ideas?