The bitcoin header contains many information. Most of them are responsible to maintain the consistency of the bitcoin blockhcain. However, there is one that is a little bit exceptional and that is the difficulty target. Difficulty target is actually related rather to on-chain governance and not strongly to the consistency of the chain. The model can be actually extended in a way that there is more than one piece of on-chain information in the block header apart from difficulty. As a general extension there can be a specific data area only for on-chain governance information for which there are special rules how they can be changed and which information is secured with the help of a merkle tree which root is written into the block header.
