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Overview

BlockHeader contains all metadata for a block including Merkle roots, gas limits, timestamps, and consensus-related fields. The block hash is computed from RLP(header). 
// Obtain block header via JSON-RPC; map fields from hex to Zig types.
// {"method":"eth_getBlockByNumber","params":["latest",false]}

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Type Definition

// Core fields: parentHash, stateRoot, transactionsRoot, receiptsRoot, logsBloom, gasLimit, gasUsed, timestamp, baseFeePerGas, withdrawalsRoot, blobGasUsed, excessBlobGas, parentBeaconBlockRoot

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Creating BlockHeader

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from

Universal constructor with all header fields. 
// Map fields per fork as needed: London (baseFeePerGas), Shanghai (withdrawalsRoot), Cancun (blobGasUsed, excessBlobGas, parentBeaconBlockRoot).

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Header Fields by Fork

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Genesis (All Blocks)

FieldDescription
parentHashHash of parent block
ommersHashHash of ommers list RLP
beneficiaryBlock reward recipient
stateRootState trie root after execution
transactionsRootTransactions trie root
receiptsRootReceipts trie root
logsBloom256-byte bloom filter for logs
difficultyPoW difficulty (0 post-merge)
numberBlock height
gasLimitMax gas for block
gasUsedTotal gas consumed
timestampUnix timestamp (seconds)
extraDataArbitrary data (max 32 bytes)
mixHashPoW mix hash (0 post-merge)
noncePoW nonce (0 post-merge)

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EIP-1559 (London Fork)

FieldDescription
baseFeePerGasDynamic base fee per gas

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Shanghai Fork

FieldDescription
withdrawalsRootMerkle root of withdrawals

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EIP-4844 (Cancun Fork)

FieldDescription
blobGasUsedTotal blob gas used
excessBlobGasExcess blob gas for pricing
parentBeaconBlockRootBeacon chain parent root

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Post-Merge Changes

After The Merge, several fields are deprecated but still present: 
// Post-merge: difficulty = 0, nonce = 0; mixHash holds RANDAO reveal

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See Also