OP_RETURN2 - Overview With the current debate over the OP_Return relay policy size limit, some have suggested OP_Return2 as a solution. Please note that there may not be a formal written proposal and the design has not been specified. Therefore our analysis or understanding could be wrong or incomplete. As far as we can tell, OP_Return2 is similar to OpenTimestamps, in that a hash commitment of the raw data goes into the blockchain, but not the data itself. The OP_Return2 proposal creates a new 65 byte onchain area for this hash commitment data, that receives a discount in a new block weight formula of 5x to 8x. This requires a softfork and the new area is the cheapest space per byte, therefore use of OP_Return2 is incentivised Possible Disadvantages * As far as we can tell, this is a blocksize limit increase, with new space available for the hash commitment. The usual disadvantages of larger blocks therefore apply * Instead of using the new space for a hash of offchain data, spammers could store spam images directly in the new available space, benefiting from even more blockspace and an ever cheaper feerate per byte. The data would be very "non-contiguous". On the other hand, there could be overhead costs, such that its not cheaper overall * The scheme seems quite similiar to what is already available with OpenTimestamps or other systems, which do not require a softfork Source: https://gist.github.com/rsantacroce/88d1ba20f52a46718be7ada6b4c8173d#solution(BitMEX Research)