X-Mining

If quasi-relaying a Bitcoin transaction to Ethereum is costlier than the reward, or the transaction is mined in some alt-chain with very little reward, miners can opt for x-mining to increase the reward share by decreasing the winning chance proportionally.

To x-mine a brand, the brand memo (in OP_RET) is appended with one space character (ASCII 0x20), an x, and the decimal string of reward multiplier number m.

OP_RET "endur.io x6"

An x-mining transaction is valid only in a block with KECCAK(BlockkHash | PubkeyFirst32Bytes) % m == 0 and the reward shared will be increased by $\times m$ times.