Forward compatible consensus data structures

The five-minute read

One action, walked through

1. Open EIP 7688 and read the status line before the examples.
2. Write down the rule in one sentence. A fair version of that sentence is: The changes needed to adopt ProgressiveContainer from EIP-7495 and ProgressiveList from EIP-7916 in consensus data structures.
3. Name the object that changes: SSZ.
4. Ask what an old client, an old contract, or an offline counterparty does. If the document is silent, the silence is part of the design.

The argument, unpacked

What has to be true

• You are implementing EIP 7688 at the status the text itself states: Review.
• The object that has to change is SSZ. A neighbouring document with a similar name is not this one.
• Parameter choices in one release are not the proof.

What happened after the paper

The source marks this review. It is not a live consensus rule just because it has a number. Later documents can narrow, replace, or ignore this one. Cite the number you mean.

What to check before you use the idea

• What does Forward compatible consensus data structures treat as decided, and what can still be reorged?
• What share of stake or hash power does the argument need?
• Which objects are defined: SSZ?

Terms

EIP 7688

The public text titled Forward compatible consensus data structures.

Review

The document's own label for how finished the text is. It is not a market fact.

The problem the paper names

A consensus change that is only described in a client does not tell an outside verifier what must be true.

What the design proposes

• The changes needed to adopt ProgressiveContainer from EIP-7495 and ProgressiveList from EIP-7916 in consensus data structures.
• Only merkleization changes; serialization of affected types is unchanged.
• Ethereum's consensus data structures make heavy use of Simple Serialize (SSZ) Container, which defines how they are serialized and merkleized.

How the mechanism is specified

• Taken from the specification, the next constraint is: Only merkleization changes; serialization of affected types is unchanged.
• Locate SSZ in EIP 7688 and apply it to one transaction or call.
• Then check the failure the class of rule always has: a node that did not upgrade, a reverted call, a replayed signature, or a peer that does not speak the message.

What this page does not treat as proven

• Final in the EIP process is not finality of a checkpoint.
• Parameter choices in one release are not the proof.
• The source marks this review. It is not a live consensus rule just because it has a number.

Why a venture studio still reads it

Use EIP 7688 when a pitch says 'Forward compatible consensus data structures' without saying whether the rule is consensus, policy, or an interface. The number is the citation. The pitch is not.