Here are the Ethereum objects as I have mapped them so far. While there are only two underlying structures (RLP and Eth-(Secure-)Trie), they interpret the format of the leaf values based on context, which is lost when resolving at the IPLD level. I sketched out some versions that used fewer IPLD formats by employing some cleverness in the path naming conventions. (see here https://github.com/MetaMask/metamask-plugin/issues/719#issuecomment-267528294). The consensus was to be explicit instead of clever, thusly the list of objects as I've proposed.
I'd additionally like to reserve 0x99-0x9f for additional Ethereum objects I may have missed or may be introduced when Ethereum milestone Metropolis is released.
Blake2s and Blake2b have different initial vectors states for different lengths, this means that for each chosen output length it looks like completely different hash function.
This proposal allocated 64 values for Blake2b and 32 values for Blake2s as those are the ranges the outputs can be chosen from.
The codes will require 3 bytes to write down as varints.
