Differences between Level-1 and Level-2 blockchains allow us to pause and reflect on observations Ward Cunningham made during yesterday's dev/user video chat and how wiki makes json page copies of wiki objects. Although wiki has no Office like Undo button, wiki is extensive in its use of json for page edits. Thinking we put toward Distributed Systems Undo.
Layer-2, Layer-1
What you need to know about different Blockchain Layer solutions page 
The Scalability Trilemma - Vitalik Buterin
Mark S Miller's Agoric is building a layer 1 Proof of Stake (PoS) public blockchain and smart contract platform, with hardened JavaScript, security delivered by the enclave environment, Zoe page