First off, the Bitcoin Cash ABC community and project are led by the Bitcoin Cash evangelist, Roger Ver and the co-founder of Bitmain, Jihan Wu. Miners supporting BCHABC include BTC.com, Antpool, and Bitcoin.com.
This version of BCH aims to preserve the original functionality and vision of the Bitcoin Cash network and currently preserves the block size of 32MB. However, because the hard fork is technically an upgrade, there are some improvements.
As mentioned in the Official Post about BCHABC, supporters of the network will take a simple 2-pronged approach to scaling.
1. “Remove immediate implementation bottlenecks to increasing the block size limit.”
2. “Lay the technical groundwork for massive future on-chain scaling.”
Additionally, the BCHABC chain has implemented code for the interoperability between cryptocurrencies, something which Bitcoin Cash didn’t have before.
What is this dispute about?
The Bitcoin Cash dispute is really between two competing factions, represented by their respective software implementations.
In one corner stands Bitcoin ABC, the “original” Bitcoin Cash client that caused the split away from the Bitcoin blockchain a little over a year ago. Led by Amaury Séchet, and with close (though unofficial) ties to major mining hardware producer Bitmain, Bitcoin ABC has a policy of hard forking about once every six months to upgrade the protocol. This time, Bitcoin ABC will introduce several changes. The first and probably main one is called “Canonical Transaction Ordering” (CTOR). While transactions can currently be included in a block in almost any order, under CTOR, transactions must be included in a specific order. The Bitcoin ABC development team believes this offers a couple of technical benefits, in part related to (future) scaling improvements.
A second change is a new piece of script (an “OP code”) called OP_CHECKDATASIG (DSV). This extends Bitcoin Cash’s features, most notably by enabling oracles (which allow for a class of smart contracts). Bitcoin ABC also introduced some smaller technical fixes, like a minimum size for transactions.
In the other corner stands nChain and its chief scientist Craig Steven Wright, whoclaims to be the man behind the monicker Satoshi Nakamoto, but has publicly only been able to produce fake evidence. Having released a relatively new software implementation named “Bitcoin Satoshi’s Vision” (Bitcoin S V), Wright says he wants to restore Bitcoin to its original protocol: the 0.1.0 version launched in 2009. After that, he’d take a rather conservative approach with few or no further protocol upgrades. To achieve this, Bitcoin SV makes a few changes relative to Bitcoin ABC right now. First, it rejects CTOR, as nChain believes the potential benefits are insufficiently proven and the risks are too high. Second, it increases the default block size limit to 128 megabytes (versus Bitcoin ABC’s 32 megabytes). And third, it reinstalls several old OP codes (with names as OP_MUL, OP_LSHIFT, OP_RSHIFT and OP_INVERT). It also removes the size limit on scripts. Down the road, Wright promises to make more changes to bring Bitcoin SV closer to the 0.1.0 version of the Bitcoin protocol. The block size limit will eventually be increased a lot more or even removed entirely. DSV will be dismantled. (Wright goes so far as to claim DSV would make Bitcoin ABC and its miners illegal. On Bitcoin SV, coins held in “DSV addresses” will likely be turned into donations to miners.) P2SH transactions (which allow for much transaction flexibility and was introduced in 2012) will be deprecated. More old OP codes will be restored. And the nChain chief scientist alluded to bringing “lost” coins back into circulation. (Where “lost” presumably refers to coins that haven’t moved in a long time.