j"1NF7i6ZoMDXaJ2Q5M9QFriH74ya6r6vP8u<MinerID allows miners to prove which blocks they have mined.MRMiners can sign a blocks proving that they mined it.
This has many legal implications one of which allow miners to prove a product was created with a certain amount of input (energy). This helps with audits and taxing.
MinerID also lets miners advertise specialization.
Current miner ID's can be viewed here: https://satoshi.io/miners
https://whatsonchain.com/tx/c6d02bd91e3c9a402d62ba729ded5fa816bcb5209563e41a77e1f92718abbb54