# Us and them

all we need from the next spec is this struct:

class SignedShardBlobHeader(Container):
    message: ShardBlobHeader
    signature: BLSSignature

https://github.com/ethereum/eth2.0-specs/blob/dev/specs/sharding/beacon-chain.md#signedshardblobheader

This is quite clever

class ShardWork(Container):
    #  Upon confirmation the data is reduced to just the header.
    status: Union[                                                   # See Shard Work Status enum
              None,                                                  # SHARD_WORK_UNCONFIRMED
              DataCommitment,                                        # SHARD_WORK_CONFIRMED
              List[PendingShardHeader, MAX_SHARD_HEADERS_PER_SHARD]  # SHARD_WORK_PENDING
            ]

https://github.com/ethereum/eth2.0-specs/blob/dev/specs/sharding/beacon-chain.md#shardwork