How to use Pallas IndexingMode?

[Lime-Cakes]

There's currently a lack of documentation on Pallas IndexingMode. There's two mode (Blocked & Unblocked)
https://github.com/google/jax/blob/945b1c3b8a78f32924cb425b56b7fdc5dd2565a8/jax/_src/pallas/core.py#L169

However, there doesn't seem to be any documentation on how exactly BlockSpec work in the two modes. Will there be doc for that in the future?

What do they do? And what is their difference?

Edit: I was not aware of #22134 while writing the issue. It contains a lot more doc related to BlockSpec, but doesn't cover Unlocked either.

[Lime-Cakes]

#22370 contains unblocked doc.