To some people, "safe hardfork" means the currency does not and cannot actually split
Thanks for your comment. In my view this is a misunderstanding, let me try to explain with some examples:
1. "Evil" hardfork - Potentially Safe
A hardfork where the new chain merge mines empty blocks on the original chain, thereby attacking it. This hardfork only occurs with extremely strong consensus. (e.g. 99% miner threshold)
2. "Strong consensus" hardfork- Potentially Safe
The hardfork occurs on the condition that there is no significant opposition in any section of the community. A minority has veto power. The activation threshold could be a 95% softfork, imposing the new rules and a hardfork which will then occur after say 6 months.
3. "Chain split" hardfork - Potentially Safe
One section of the community disagrees with another part of the community and wants to go in a different direction. A flag day or checkpoint is set when the two chains diverge. A strategy is in place to mitigate the replay attack problem. There is no activation threshold and miner support for the new chain can be very small or high, e.g. 1% or 75%. The Ethereum vs Ethereum Classic hardfork was similar to this
4. Harkfork with large mining split and asymmetric advantage - Unnecessarily dangerous
e.g. BitcoinXT, Bitcoin Classic, BU
There is a hardfrok attempt that activates at a specific miner threshold that ensures both chains may survive, e.g. 75% vs 25%. (Even worse there is rolling voting, unnecessarily
guaranteeing a significant miner split, rather than voting windows, which only makes a large miner split possible). At the same time the original chain has the ability to "wipe out" the new chain if it becomes longer than it, erasing its history and
causing loss of funds. The characteristic that people lose funds makes this method dangerous. It is unnecessarily dangerous in that there is no advantage in allowing the funds to be erased. However the new chain can never wipe out the old chain. This type of hardfork is particularly dangerous as the more successful the new chain is, the more compelling it is for speculators to try and erase it and make profits.
@freetrader, I think the above illustrates what many mean by a "safe" or "dangerous" hardfork. "Safe" does not necessarily mean two chains cannot survive (See type 3). I would kindly ask again that the campaigning for a "type 4" hardfork ends, it is simply not necessary. You can achieve your objectives with a type 2 or type 3 hardfork quite easily. (As I explained many times, many are very happy for a type 2 hardfork, they just do not want to do this during an attempt at a "type 4")
