Update stacks-l2.md

stacks-l2.md

@@ -7,9 +7,11 @@ The initial release of Stacks in early 2021 had a separate security budget from
 
 The upcoming planned release of Stacks, called the Nakamoto release (convention to use names of famous Computer Scientists for major releases), will no longer have a separate security budget from Bitcoin. Instead, a 100% of Bitcoin hashpower will determine finality on Stacks layer. After the next upgrade, to reorg Stacks blocks/transactions the attacker will need to reorg Bitcoin L1 itself (which is very hard to do and therefore a great security property for a Bitcoin layer to have). More details in the [Stacks paper](https://stacks.co/stacks.pdf).
 
-The definition of [L2 used in Ethereum](https://ethereum.org/en/layer-2/) and other newer ecosystems is different and focuses on the ability to withdraw assets using only L1 security and L1 miners. According to that definition Stacks layer is not a clear L2, given the set of peg-out signers determine if users can withdraw sBTC. Bitcoin cannot support such verification without changes to Bitcoin L1 (which may happen in the future). The Ethereum L2 definition also does not apply that cleanly to Bitcoin L2s, given new assets are issued on L2s when it comes to Bitcoin and not issued on L1 (only BTC is the L1 asset). Therefore, using the definition of security of withdrawing assets is not directly applicable given assets are defined and used on L2s and not withdrawn out to Bitcoin L1 anyway (with the exception of BTC itself). Rather, what becomes more important is "settlement on Bitcoin" i.e., is contract data and state secured by 100% of Bitcoin's hashpower or not.
+The definition of [L2 used in Ethereum](https://ethereum.org/en/layer-2/) and other newer ecosystems is different and focuses on the ability to withdraw assets using only L1 security and L1 miners. According to that definition Stacks layer is not a clear L2, given the set of peg-out signers determine if users can withdraw sBTC. Bitcoin cannot support such verification without changes to Bitcoin L1 (which may happen in the future). The second property of L2s is that you typically need to attack the underlying L1 to reorg the L2, called reorg resistance. Stacks, after Nakamoto release, will have Bitcoin reorg resistance making it closer to a L2.
 
-Users and developers organically call Stacks a Bitcoin L2, since it is a simpler concept to understand. There are certain properties of Stacks layer that also help the concept of Stacks as a Bitcoin L2:
+Using the strict technical definition of only L1 security used for withdrawing assets from L2, Lightning will be the only Bitcoin layer that'd qualify today. However, if also considering the reorg resistance dimension then Stacks starts to look closer to a L2 with a potential path where once/if Bitcoin L1 introduces new opcodes then BTC can be withdrawn out from Stacks L2 using only Bitcoin L1 security (and no need for decentralized signers).
+
+The term L2 has been widely used in the Bitcoin community even before Ethereum existed. Users and developers organically call Stacks a Bitcoin L2, since it is a simpler concept to understand. There are certain properties of Stacks layer that also help the concept of Stacks as a Bitcoin L2:
 
 1) Bitcoin finality, as discussed above, where 100% of the Bitcoin hashpower decides block ordering and transaction finality. 
 2) Stacks consensus runs on Bitcoin L1, and Stacks L2 cannot operate or survive without Bitcoin L1.
@@ -19,10 +21,10 @@ Users and developers organically call Stacks a Bitcoin L2, since it is a simpler
 
 Given all the details above, why would some people think that Stacks is not a Bitcoin L2? There are a couple of reasons why this question comes up often:
 1) The initial version of Stacks (released early 2021) had a separate security budget which changed to following 100% Bitcoin hashpower with the Nakamoto release. There is old material and blog posts floating around that still talk about the initial Stacks version. The old materials will likely get updated with time.
-2) According to the Ethereum definition of L2s a user should be able to withdraw their base-layer assets purely by doing a L1 transaction and relying only on L1 security (this is true for Lightning for example). This definition does not apply cleanly to Bitcoin L2s because assets are not defined at Bitcoin L1 but are defined in L2s instead. The only asset where this matters is the pegged BTC asset from Bitcoin L1, given all other assets are native to L2s anyway. In the upcoming Stacks release, users can withdraw their BTC by sending just a Bitcoin L1 transaction but Bitcoin L1 cannot validate that complex transaction and a majority of peg-out signers will need to sign on the peg-out request. In an ideal world Bitcoin miners can validate such transactions but that would require a change to Bitcoin L1. Therefore, Stacks design optimizes for a method that is decentralized and can be deployed without any changes to Bitcoin L1. If in the future it is possible to make changes to Bitcoin L1 then Stacks layer security can benefit from that as well.
+2) According to the Ethereum definition of L2s a user should be able to withdraw their base-layer assets purely by doing a L1 transaction and relying only on L1 security (this is true for Lightning for example). In an ideal world Bitcoin miners can validate such transactions but that would require a change to Bitcoin L1. Therefore, Stacks design optimizes for a method that is decentralized and can be deployed without any changes to Bitcoin L1 today. If in the future it is possible to make changes to Bitcoin L1 then Stacks layer can benefit from that as well.
 3) Bitcoin community members are generally skeptical of claims and on a look out for people making any false marketing claims. This is generally a healthy thing for the Bitcoin ecosystem and builds up the immune system. Some such community members might be skeptical about Stacks as a Bitcoin layer or L2 until they fully read the technical details and reasoning. There is a [good Twitter thread](https://twitter.com/lopp/status/1623756872976158722?s=20) about his topic as well.
 
-Why don't we use the term 'sidechain' for Stacks then? Sidechains in Bitcoin typically have a different security budget from Bitcoin L1, typically as a subset of Bitcoin miners who participate in the sidechain (they don't follow 100% Bitcoin finality), their consensus runs on the sidechain (vs running on Bitcoin L1), and they don't publish their data/hashes on Bitcoin L1. The Stacks layer does not fit that definition cleanly given the consensus runs on Bitcoin L1, it follows Bitcoin finality, and publishes data/hashes on L1.
+Why don't we use the term 'sidechain' for Stacks then? Sidechains in Bitcoin typically have a different security budget from Bitcoin L1, typically as a subset of Bitcoin miners who participate in the sidechain (they don't follow 100% Bitcoin finality), their consensus runs on the sidechain (vs running on Bitcoin L1), and they don't publish their data/hashes on Bitcoin L1. The Stacks layer does not fit that definition cleanly given the consensus runs on Bitcoin L1, it will follow Bitcoin finality, and publishes data/hashes on L1.
 
 The TLDR is that it is better to refer to Stacks as a Bitcoin layer (the more generic term). However, the Bitcoin L2 term is more organic and simpler for users and we'll likely keep seeing the use of it. If the Bitcoin L2 term comes up then it's important to understand the technical differences and that unlike Ethereum L2s withdrawing BTC from Stacks requires signatures from peg-out signers.