A simple fact of life is that no one can always effectively dictate rules for others so chain split is inevitable. Knowing that the price of a coin is only related to its energy power K and volume V, then in case there are multiple energy powers for the coin, the energy power for this coin's pricing is simply the sum of those energy powers. This happens when the blockchain forks.
Suppose there are n blockchains with different validation rules after the fork with energy power K1 to Kn and the total energy power is K = K1+K2+...+Kn, a coin created before the fork now may be valid in all rules or not. Suppose it is valid in blockchain 1 to blockchain m, then its price shall be (K1+..+Km)/qV. A consequence is that the coins in the same blockchain is not necessarily with the same price.
In typical forks with replay possibility, a legacy coin is usually valid for all the newly n rules and the legacy rule is one of the n rules. That means its price remains the same after the fork because (K1+...+Kn)/qV is the same as K/qV. Isomorphically, this is an energy distribution scheme. Note that the coins valid in all chains enjoy highest and stable price thanks to law of energy conservation.
The legacy blockchain forks into two blockchains with replay protection. Then any coin in a specific blockchain is invalid in the other blockchain. Therefore, the price of all coins in blcokchain 1 is reduced to K1/qV and the price of all coins in blockchain 2 is reduced to K2/qV. This must be bad for merchants because they have to update all the sale prices in their catalog.
A group of tyrants decides to invalidate all coins except the coins ever going through their addresses before 2016-1-1 or source from newly mined coins from the tyrants' miners. However, this is not agreed by the global community. The legacy blockchain forks into two blockchains, chain 1 being the legacy chain, chain 2 being the tyrant chain. For coins valid in rule 1 and rule 2, its price remains K/qV as before the fork. For coins valid in rule 1 but invalid in rule 2, its price slightly reduced to K1/qv. For coins valid in rule 2 only, its price is low at K2/qV. This must be good for libertarian.
The permission less nature of bitcoin allows not only software tool innovation but also bitcoin rules evolution. Suppose a developer has an interesting idea/rule but sadly agrees to disagree by a majority of community and only a handful of miners support his idea. Traditionally, all the developer can do is to launch a new altcoin and possibly takes years to establish the economy around this new coin. This is a huge cost and highly possible the developer will let go the idea and the coin fails due to lack of network effect.
Suppose there are 2 block chains alive and bitcoin is defined as coins valid in all alive block chains. With the replay benefit, the developer can launch the idea in a new chain forked at a specific block height of chain 2. Initially maybe only a negligible amount of mining power supports the third chain but the sweet part is that all people have their coins with the new idea without notice. The coins which are only valid in this new chain are of course near to zero price initially. As time goes by, thanks to the economic activity of all people, more mining powers commit to chain 3 and dismiss from chain 2. While the total energy power remains the same, the percentage of mining power of chain 3 is then visible and the bitcoin is always defined as coins valid in all alive chains without loss of price and economy. Further, the new idea is so good that chain 2 dies out and the bitcoin is now the coins valid in chain 1 and chain 3, also valid in all chains. This must be good for a peaceful evolution of bitcoin rules.
Knowing the developing history so far in bitcoin, the only logical way to define currency code is as below.
This is the ordering of the price as well as the ordering of price stability. Coins are represented by the 2-tuple (address, satoshi amount). People shall focus on the coins recorded in all significant chains for the sake of economic interest.