Is there a specific standard documented somewhere that this crate adheres to?

[McFranko]

title

[taegyunkim]

Some comments in this repository refers to V2 https://github.com/filecoin-project/bls-signatures/blob/0da49c1c8eb7bdea9c531dc873a9a8432f88a35b/src/signature.rs#L144 I don't know either whether this crate implements newer drafts.

By default, this crate uses bls12_381 v0.7.0 with experimental feature, and that implements Hashing to Curves V12 https://github.com/zkcrypto/bls12_381/blob/34dab74ae44cd77dfa867928dd2e6c8383d8dc9d/README.md?plain=1#L18