Auxiliary Proof of Work (AuxPoW)
The specific technical standard that embeds a primary chain's block header inside an auxiliary chain's block, enabling merge mining between them.
Auxiliary Proof of Work, or AuxPoW, is the specific technical standard and data structure used to implement merge mining (see Kaavon's "Merge Mining" glossary definition): it defines how an auxiliary chain's block embeds a reference to, and proof of inclusion in, a block header from the primary chain being merge-mined, so that validating nodes on the auxiliary chain can independently verify the primary chain's proof-of-work actually commits to the auxiliary chain's data. Without this standardized structure, there would be no reliable, verifiable way to link the two chains' mining together.
AuxPoW is specifically the protocol-level mechanism, whereas merge mining is the broader practice or strategy it enables — a chain can only be merge-mined with another chain if both implement a compatible AuxPoW structure allowing one chain's miners to embed proofs referencing the other. Different chains have historically implemented their own variations of this standard, so AuxPoW compatibility isn't universal across all proof-of-work blockchains.
Examples
- A node validating an AuxPoW block checks that the embedded primary-chain block header genuinely satisfies both chains' difficulty requirements before accepting the auxiliary chain's block as valid.
- Two proof-of-work chains can only merge-mine with each other if both implement compatible AuxPoW support — it isn't an automatic feature of all proof-of-work blockchains.