# PeepAnEIP-7549 @dapplion --- - What's an attestation committee index? - Why do we want to remove it - Why was there on the first place - Misc and other consenquences ---  _ref: https://ethos.dev/beacon-chain_ --- ```python class AttestationData(): slot: Slot index: CommitteeIndex <= 🤡 # LMD GHOST vote beacon_block_root: Root # FFG vote source: Checkpoint target: Checkpoint ``` --- ### Benefits of removing it  --- ### Benefits of removing it - 64x more efficient light-clients - More efficient packing on-chain - More efficient attester slashings --- ### 64x more efficient light-clients  --- ### 64x more efficient light-clients  --- ### 64x more efficient light-clients Worst offenders for ZK proving: - Pairings - Hashing (sha256) --- ### More efficient packing on-chain ```python class Attestation(): aggregation_bits: Bitlist[MAX_VALIDATORS_PER_COMMITTEE] data: AttestationData signature: BLSSignature ``` --- ### More efficient packing on-chain ```python class Attestation(): aggregation_bits: Bitlist[MAX_VALIDATORS_PER_SLOT] data: AttestationData signature: BLSSignature committee_bits: Bitvector[MAX_COMMITTEES_PER_SLOT] ``` --- ### More efficient packing on-chain  --- ### Why was there in the first place?  --- ### Old times, execution shards  --- ### But, pivot to rollups  --- ### Too late for phase0..  --- ### Security considerations - Mutation over gossip - First block after fork - Deprecation strategy --- ### First block after fork  --- ### Deprecation strategy - Removing the field - Setting to fixed zero - Changing to Optional with EIP-7495 StableContainer --- ### Status  ---  --- # PeepAnEIP-7549 @dapplion ## _Thank you!_