EIP complexity assessment

EIP-5656: MCOPY - Memory copying instruction

Assessed in Cancun / Dencun. The score describes the EIP text available at the assessment cutoff, not the EIP as it stands today.

RetrospectiveCancun / DencunAssessment cutoff 2023-05-25Included by cutoffLayers: execution

LLM Completescore 9

Human Not available· Human complexity assessments were not produced for this fork; only the LLM assessment exists.

LLM assessment

Evaluated on: 2026-08-25 · Spec revision: 2023-05-11 · e9b6a228f0

Scope at the cutoff. At the 2023-05-25 information cutoff, EIP-5656 introduced the single MCOPY instruction at opcode 0xb7 to copy an arbitrary byte range within EVM memory. It specified three stack inputs, no output, memmove-like overlap semantics, memory expansion, and dynamic gas by adding the instruction to the existing W_copy group. The proposal did not change state, transactions, blocks, interfaces, precompiles, or system contracts.

9LowLow

Evaluator: LLMChecklist v2
Confidence: High
Under-specified at assessment cutoff: No
Plausible range: 9–9 (Low)
Assessment cutoff: 2023-05-25 · EIP revision e9b6a228f0 (2023-05-11)

Score bands · Checklist revision 2

Low <12
Medium 12–22
High ≥23

28 criteria scored 0–3 (4 in exceptional cases; cross-EIP interactions is uncapped); nominal maximum 84.

Complexity profile

Each segment is one criterion's contribution to the LLM total. Hover or focus a segment for its score and rationale.

Under-specified at assessment cutoff: No

The EIP text available at the assessment cutoff left material behavior unresolved. The affected criteria and the plausible total range record that uncertainty.

The assessor found no material behavior left unresolved by the EIP text at the cutoff.

Notable ambiguities noted by the assessor (1)

The security-considerations section is TBA, which limits explicit risk analysis but does not leave MCOPY execution behavior unresolved.

Criterion breakdown

EIP-5656 Cancun / Dencun: LLM criterion scores and rationale
Criterion	Score	Why this score	Evidence / uncertainty
Edge/boundary conditions	3	Several independent boundary-prone dimensions are introduced: zero versus nonzero length, 32-byte rounding and partial words, overlap direction and equality, and expansion caused by either range. Overlap and expansion must also be combined across arbitrary offsets and lengths, producing an elevated case matrix; this meets score 3.	eip.md · Motivation, lines 26-33; Gas costs and Semantics, lines 71-93 The proposal covers arbitrary offsets and lengths, per-word rounding, partial words, overlap via intermediate-buffer semantics, the zero-length guard, and source- or destination-driven memory expansion. eip.md · Test Cases, lines 108-161 The examples separately exercise an ordinary copy, identical source and destination, and overlaps in both directions. Confidence: High
Added opcodes	2	This is a single complex opcode because it processes a variable data portion and has dynamic gas. It therefore matches the score-2 anchor exactly.	eip.md · Specification, lines 57-93 The EIP introduces one opcode, MCOPY at 0xb7, taking destination, source, and length, copying a variable-size memory region, and charging dynamic per-word plus memory-expansion gas. Confidence: High
EVM Gas rule changes	1	The proposal extends an existing EVM gas-accounting mechanism to one new opcode. This matches score 1: an existing mechanism is updated, rather than a distinct new mechanism being introduced or existing opcode gas changing.	eip.md · Gas costs, lines 71-80; Semantics, lines 91-93 MCOPY is assigned to the existing W_copy opcode group, with very-low base gas, a per-word copy charge, and the ordinary memory-expansion charge. Confidence: High
Patterns affecting pre-existing tests	1	A narrow subset of pre-fork tests exercising the formerly invalid opcode or fork-transition bytecode behavior must be reworked. That is the minor-subset impact described by score 1, not a broad rewrite of existing tests.	eip.md · Backwards Compatibility, lines 102-104 Opcode 0xb7 changes from a previously nonexistent instruction to MCOPY, and the EIP notes that already-deployed code using it can change behavior. Confidence: High
Security risks	1	Incorrect overlap, bounds, or gas handling could create divergent execution, but the mechanism is self-contained and testable in isolation and does not alter state or cross-component security invariants. This matches score 1.	eip.md · Semantics, lines 86-93; Security Considerations, lines 164-166 The new mechanism is confined to memory copying, overlap behavior, dynamic copy gas, and memory expansion, while the security section remains TBA. Confidence: Medium Uncertainty: The historical proposal contains no substantive security analysis, so the risk classification rests on the specified memory-only scope.
Performance risks	1	Variable-size copying warrants validating that implementation work tracks its gas schedule, but the opcode is memory-only and can be benchmarked directly across lengths and overlap cases. It does not alter the performance path of existing opcodes, matching score 1.	eip.md · Motivation, lines 35-55; Gas costs and Semantics, lines 71-93 MCOPY is intended to accelerate common and computationally heavy memory copying, while accepting an arbitrary length and charging per copied word plus memory expansion. Confidence: High

Show 22 zero-score criteria

Zero-score criteria (Checklist revision 2)
Criterion	Why this score	Evidence / uncertainty
Modified opcodes	Adding MCOPY is scored under Added opcodes, while no existing opcode behavior is modified; this criterion is score 0.	eip.md · Specification, lines 57-93; Backwards Compatibility, lines 102-104 The proposal creates a previously nonexistent instruction at 0xb7; it does not change the result or deprecate any pre-existing opcode.
Added precompiles	No precompile is added, so the score-0 anchor applies.	eip.md · Motivation, lines 21-24; Specification, lines 57-59 The existing identity precompile is discussed only as an alternative; the actual proposal introduces MCOPY as opcode 0xb7.
Modified precompiles	The identity precompile remains unchanged and no other precompile is altered; this criterion scores 0.	eip.md · Motivation, lines 21-24; Rationale, lines 95-100 The document compares MCOPY with the existing identity precompile and its call overhead but specifies no change to that precompile's logic or gas.
Added system contracts	No system contract is introduced, so this criterion scores 0.	eip.md · Specification, lines 57-93 The proposal adds opcode 0xb7 directly to the EVM and specifies no contract address, code deployment, persistent state, or system action.
Modified system contracts	No pre-existing system contract is directly or indirectly modified; score 0.	eip.md · Semantics, lines 86-93 MCOPY's effects are confined to the executing frame's memory and do not call, read, write, or otherwise identify a system contract.
State-access ordering within opcode execution	No opcode state access is added or reordered, and no gas charge is moved relative to a state access, so the score-0 anchor applies.	eip.md · Semantics, lines 86-93 The instruction reads and writes only EVM memory and charges for copying and memory expansion; it performs no account or storage access.
Blob gas accounting changes	No blob resource or blob-gas rule is introduced or changed; this is score 0.	eip.md · Abstract, lines 13-15; Gas costs, lines 71-80 The proposal is limited to memory copying and specifies only ordinary EVM opcode gas and memory-expansion gas.
State gas accounting changes	The proposal has no state-gas charging site, budget, reservoir, or spill interaction, satisfying the score-0 anchor.	eip.md · Semantics, lines 86-93 MCOPY changes transient memory only and its gas schedule contains copy and memory-expansion costs, not charges for writing persistent state.
New EVM gas refund	No gas-refund mechanism is introduced, so the score-0 anchor applies.	eip.md · Gas costs, lines 71-80; Semantics, lines 91-93 The specification defines gas charged for MCOPY and memory expansion but defines no refund behavior.
New transaction types	No transaction type is introduced, so this criterion scores 0.	eip.md · Abstract, lines 13-15; Specification, lines 57-93 EIP-5656 introduces an EVM memory instruction and contains no transaction envelope or transaction-type definition.
New or modified transaction validity mechanisms	Existing transaction validity and intrinsic gas are unchanged; score 0.	eip.md · Specification, lines 57-93 The specification governs execution of MCOPY after valid bytecode is run; it defines no transaction admission, validity, or intrinsic-gas rule.
New block / header fields	No block or block-header field is added, so this criterion scores 0.	eip.md · Specification, lines 57-93 The proposal's complete specified data consists of an opcode's stack inputs and memory effects; it introduces no block or header value.
Encoding changes (RLP/SSZ)	No RLP, SSZ, transaction, block, or interface encoding changes; score 0.	eip.md · Specification, lines 57-93 The proposal defines an opcode byte, stack operands, and memory semantics, without changing transaction, block, or interface serialization.
Block syncing changes	Block RLP validation and client syncing are unchanged, satisfying score 0.	eip.md · Specification, lines 57-93 The only consensus rule added is an EVM instruction over stack and memory; no block encoding or RLP validation rule is specified.
New fork activation mechanism	Ordinary fork-gated opcode availability is not the state/internal-variable mutation covered by this anchor; no new activation mechanism exists, score 0.	eip.md · Specification, lines 57-93; Backwards Compatibility, lines 102-104 Activation makes opcode 0xb7 execute as MCOPY, but the EIP prescribes no activation-block state write or modification of an internal variable.
Engine API changes	No Engine API field, endpoint, or communication mechanism changes; score 0.	eip.md · Specification, lines 57-93 The feature is completely specified as an EVM opcode and defines no execution/consensus-client communication field or endpoint.
Transition-tool interface changes	The transition-tool interface needs no field or mechanism change, matching score 0.	eip.md · Specification, lines 57-93 All specified inputs and outputs belong to the EVM operand stack and memory; no transition-tool request or response field is introduced.
New invariant on pre-existing tests	Existing tests not concerned with MCOPY gain no cross-cutting assertion, so this criterion scores 0.	eip.md · Specification, lines 57-93; Test Cases, lines 106-161 The specification and examples define results for executions that invoke MCOPY; they do not define a new output that unrelated tests must assert.
New test-framework primitives	Standard bytecode execution, gas, failure, and memory-result assertions can express the feature's tests; no new expectation or modifier primitive is required by the text. This matches score 0.	eip.md · Test Cases, lines 106-161 The examples are ordinary opcode executions expressed as pre- and post-memory values, including same-range and overlapping copies.
Cryptography	No cryptography is introduced or modified, so the score-0 anchor applies.	eip.md · Abstract, lines 13-15; Semantics, lines 86-93 MCOPY copies bytes within memory and introduces no cryptographic function or verification mechanism.
Cross-EIP interactions	The cited EIP-2929 change explains why an alternative copying technique has particular overhead, but EIP-5656 neither depends on, modifies, nor conflicts with EIP-2929. The feature can be implemented and tested independently, so it is self-contained under the score-0 anchor.	eip.md · Motivation, lines 21-24 and 35-47; Rationale, lines 95-100 EIP-2929 appears only in the economic comparison with memory copying through CALL to the identity precompile; MCOPY itself is independently specified. supporting/eip-2929.md · Abstract, lines 16-18; Storage read changes, lines 58-71 EIP-2929 changes state-access and CALL-family costs and exempts precompiles; it defines no rule on which MCOPY's semantics or gas calculation depends.
Unspecified behavior requiring cross-client consensus	Every proposal-specific constructible case is determined by the supplied rules together with the explicitly incorporated existing W_copy calculation; no localized detail is left for clients to agree before baselining tests. The score-0 anchor applies.	eip.md · Specification, lines 57-93 The text fixes the opcode byte, stack ordering, output arity, W_copy gas basis, byte-copy result, intermediate-buffer overlap semantics, and the condition and cost for memory expansion. eip.md · Test Cases, lines 108-161 Concrete results cover ordinary, identical-range, and both directional overlap cases, reinforcing the specified copy semantics.

Assessment provenance

Assessed EIP revision: ethereum/EIPs@e9b6a228f0 EIPS/eip-5656.md committed 2023-05-11 · information cutoff 2023-05-25
Current master · File history · blob 3682a57c25 · sha256 96c6320bdf15
Rubric: Checklist revision 2 · ethspecs/pm@3d8c0128c5
Evaluator: gpt-5.6-sol at xhigh reasoning effort · isolation bubblewrap_one_eip_capsule_v1
Source record: Frozen research record research/tasks/05-retrospective-complexity-assignment/outputs/fork-eips/cancun/eip-5656.yaml · sha256 a7414c59426f
Supporting documents in the sealed package: supporting/eip-2929.md

Compare EIP-5656 with other assessments All Cancun / Dencun assessments

Criterion legend and glossary

Every stacked bar, comparison matrix, and criterion table on this site uses the same criterion colours, abbreviations, and order. Colour marks the criterion group; the abbreviation and name identify the criterion. Scores are 0–3 per criterion (4 is exceptional; cross-EIP interactions is uncapped).

EVM surface

Opcodes, precompiles, and system contracts that are added or modified.

OP+
Added opcodes
Introduces new opcodes
Score anchors
0
No new opcodes are introduced.
1
A new simple opcode is introduced (no data portion, no complex stack mechanics, and a constant gas cost).
2
Multiple new simple opcodes are introduced, or a single new complex opcode is introduced (has data portion, or complex stack mechanics, or a dynamic gas cost).
3
Multiple new opcodes are introduced, and at least one of them is complex (has data portion, or complex stack mechanics, or a dynamic gas cost).
- Cryptography opcodes are not considered complex by default. Refer to the "Cryptography" section for a separate assessment.
Modified opcodes
Modifies pre-existing opcodes
Score anchors
0
No pre-existing opcode modifications are introduced.
3
At least one pre-existing opcode's behavior is modified (not including gas changes) or a pre-existing opcode is deprecated.
PC+
Added precompiles
Introduces new precompiles
Score anchors
0
No new precompiles are introduced.
1
A new simple precompile is introduced (constant input length, constant gas cost).
2
Multiple new simple precompiles are introduced, or a single new complex precompile is introduced (dynamic input length or dynamic gas cost).
3
Multiple new precompiles are introduced, and at least one of them is complex (dynamic input length or dynamic gas cost).
- Cryptography precompiles are not considered complex by default. Refer to the "Cryptography" for a separate assessment.
Modified precompiles
Modifies pre-existing precompiles logic or gas-accounting
Score anchors
0
No pre-existing precompiles are modified.
1
At least one pre-existing precompile has its gas schedule modified.
2
Multiple pre-existing precompiles have their gas schedule modified, or a single pre-existing precompile has its behavior modified.
3
The behavior of multiple pre-existing precompiles, or a single complex pre-existing precompile modified.
Added system contracts
Introduces new system contract, stateful or not
Score anchors
0
No new system contracts are introduced.
1
A new system contract is introduced that is not stateful nor does it trigger a new system action (e.g. requests to the consensus layer).
2
Multiple new system contracts are introduced or a single new system contract that is either stateful or triggers a new system action (e.g. requests to the consensus layer).
3
Multiple new system contracts are introduced and at least one of them is either stateful or triggers a new system action (e.g. requests to the consensus layer).
Modified system contracts
Modifies pre-existing system contracts
Score anchors
0
No modifications to pre-existing system contracts are introduced, directly or indirectly.
1
Does not directly modify any system contract, but its behavior has minor indirect effects on one or more system contracts.
2
Does not directly modify any system contract, but its behavior has major indirect effects on one or more system contracts.
3
At least one pre-existing system contract code or state is modified, which would involve irregular state transition or a similarly complex transition methodology.

Gas and accounting

Execution, blob, and state gas rules, refunds, and where charges happen inside opcodes.

EVM Gas rule changes
New EVM gas accounting rules
Score anchors
0
No gas accounting changes.
1
Existing gas accounting mechanism is updated.
2
A new gas accounting mechanism is introduced but it does not affect existing mechanisms nor does it affect existing tests.
3
A new gas accounting mechanism is introduced and affects existing mechanisms which in turn affect existing tests.
ORD
State-access ordering within opcode execution · Checklist revision 2 only
Changes *where inside an opcode's execution* state is accessed, or where gas is charged relative to that access. Because a state access is recorded in the block-level access list only if execution had enough gas to reach it, this ordering is consensus-critical: moving it changes the BAL at every gas boundary of every affected opcode.
Score anchors
0
No change to where state is accessed, or to where gas is charged relative to a state access, within any opcode.
1
A single opcode's state-access or gas-charge ordering changes.
2
Multiple opcodes' ordering changes, or a new state-accessing operation is introduced whose position in the order must be settled.
3
The ordering rule changes for a whole class of state-accessing opcodes at once, or what counts as a recordable state access is redefined — requiring existing BAL vectors to be re-derived across opcodes and forks.
- Distinct from "Modified opcodes", which asks whether an opcode's **result** changed. This row asks about the **path to the result**, which is observable even when the result is identical. An EIP can be 0 on that row and 3 on this one.
- Score changes **to** the ordering. Do not score the fact that state accesses are observable — they always are.
- Each boundary must be re-tested against every other dimension that can change the answer (cold/warm, static/non-static, delegated/direct, revert/success), so the case count grows multiplicatively rather than additively. Note this explicitly under Special Considerations.
Blob gas accounting changes
New Blob gas accounting rules which potentially affect pre-existing tests
Score anchors
0
No blob gas accounting changes.
1
Existing blob gas accounting mechanism is updated.
2
A new blob gas accounting mechanism is introduced but it does not affect existing mechanisms nor does it affect existing tests.
3
A new blob gas accounting mechanism is introduced and affects existing mechanisms which in turn affect existing tests.
SGAS
State gas accounting changes · Checklist revision 2 only
New state gas accounting rules. State gas is the cost of *writing* state, as opposed to accessing or executing it: `StateGasCosts`, `COST_PER_STATE_BYTE`, the block-level state gas budget, and the spill path into execution gas.
Score anchors
0
No state gas accounting changes.
1
An existing state gas cost or `STATE_BYTES_PER_*` rate is adjusted.
2
A new state-gas-charging site is introduced, or the block-level state gas budget or reservoir allocation is modified.
3
A new state gas charging mechanism is introduced, or the spill interaction between state gas and execution gas is modified, affecting existing gas tests.
- Harder to test than blob gas: the spill path means state gas cannot be metered independently of execution gas, and some costs (e.g. `NEW_ACCOUNT`) are state-dependent.
New EVM gas refund
New gas-refund mechanism
Score anchors
0
No new gas-refund mechanisms are introduced.
1
A new simple gas-refund mechanism is introduced that does not affect either existing tests or existing gas-refund mechanisms.
2
A new complex gas-refund mechanism is introduced or a simple mechanism that affects existing tests or existing gas-refund mechanisms.
3
A new complex gas-refund mechanism is introduced that affects existing tests or existing gas-refund mechanisms.

Blocks, transactions, and encoding

Transaction types and validity, block and header fields, encodings, syncing, and activation-time changes.

New transaction types
Introduces a new transaction type
Score anchors
0
No new transaction types are introduced.
3
A new transaction type is introduced.
New or modified transaction validity mechanisms
Creates new or modifies pre-existing transaction types' validation mechanisms
Score anchors
0
No changes are introduced to the validity rules of existing transaction types or to their intrinsic gas cost calculation.
1
Minor adjustments are introduced to validity rules or intrinsic gas cost calculation, but they do not significantly affect existing tests.
2
Changes to validity rules or intrinsic gas cost calculation affect existing tests, but require only limited updates to test cases and no redesign of the testing infrastructure.
3
Changes to validity rules or intrinsic gas cost calculation require extensive rework or redesign of the tests or testing infrastructure.
New block / header fields
Introduces new block or block header fields
Score anchors
0
No new block or header fields are introduced.
3
A new block or header field is introduced.
ENC
Encoding changes (RLP/SSZ)
Introduces encoding changes at the transaction/block/interfaces level
Score anchors
0
No encoding changes are introduced at the transaction, block, or interfaces levels.
3
An encoding change is introduced at transaction, block or interfaces level (e.g. RLP -> SSZ).
- "Interfaces level" includes the Engine API. Score an Engine API encoding change (e.g. JSON -> SSZ) here.
Block syncing changes
Modifies block RLP validation mechanisms that require test client syncing.
Score anchors
0
No new RLP validation mechanism is introduced.
1
A single simple RLP validation mechanism is introduced.
2
Multiple simple RLP validation mechanisms are introduced or a single complex one.
3
Multiple RLP validation mechanisms are introduced and at least one of them is deemed complex.
ACT
New fork activation mechanism
Modifies state, internal variables, or similar, at the fork activation block
Score anchors
0
No state modifications, internal variables or similar are modified at the fork activation block.
3
Either a state modification or internal variables are modified at the fork activation block.
- Initialization of new internal variable is not considered a modification.

Client interfaces

Engine API and transition-tool interface changes.

Engine API changes
Introduces new fields to the Engine API directives
Score anchors
0
No new fields or communication mechanisms are introduced to the Engine API.
1
A single new field is introduced in one of the Engine API endpoints.
2
Multiple fields are introduced to one or multiple Engine API end points, or a new Engine API end-point is introduced.
3
Multiple fields are introduced to one or multiple Engine API end points and a new Engine API end-point is introduced.
Engine API encoding changes · Checklist revision 1 only
Engine API encoding changes (the revision-1 template defines no anchor text for this row).
T8N
Transition-tool interface changes
Modifies or adds new fields to the transition tool interface.
Score anchors
0
No modifications to the transition tool interface are required.
1
A single new field needs to be introduced to the transition tool interface.
2
Multiple new fields or a new mechanism has to be introduced to the transition tool interface.
3
Multiple new fields and a new mechanism has to be introduced to the transition tool interface.
- Special consideration must be paid to this section if the EIP introduces a mechanism that requires the state transition tool to be aware whether the block it is processing is the fork-activation block.

Testing impact

Rework, new invariants, and new primitives required in the test framework.

Patterns affecting pre-existing tests
Implements a new validation mechanism or rule that translates in reworking pre-existing tests
Score anchors
0
No pre-existing tests are affected by this change.
1
Minor subset of existing tests are affected by this change.
2
Considerable subset of existing tests are affected by this change but involves only a contrived category of tests.
3
Major subset of existing tests are affected, including diverse category of tests (benchmarks, static, multiple forks, etc.).
INV
New invariant on pre-existing tests · Checklist revision 2 only
Tests that are **not about this EIP** must nonetheless assert something this EIP produces. Their logic does not change; they gain a new thing to check.
Score anchors
0
Pre-existing tests assert nothing new.
1
A narrow, contrived category of pre-existing tests gains a new assertion.
2
A broad category gains a new assertion, applied mechanically.
3
Every test in the fork gains the assertion regardless of what it tests, and pre-fork vectors must be re-derived to satisfy it.
- Paired with the row above, and easy to confuse with it. "Patterns affecting pre-existing tests" asks whether existing tests must be **reworked**; this row asks whether they must **additionally assert something new**. Score both — an EIP can be low on one and high on the other.
New test-framework primitives · Checklist revision 2 only
Requires new abstractions in the test framework itself — expectation types, modifiers, helpers — beyond writing test functions with what already exists.
Score anchors
0
Existing test primitives suffice.
1
Existing primitives need minor extension.
2
New expectation or modifier primitives are required, reusable within this EIP's own test suite.
3
New framework-level primitives are required that become a permanent part of the framework and are used by other EIPs' tests.

Risk and validation

Security, performance, boundary conditions, and cryptography that need validation.

Security risks
Introduces or modifies mechanisms that could compromise the security of the chain, users, validators, or other stakeholders, if not implemented properly.
Score anchors
0
No new mechanisms are introduced that could pose a security risk.
1
The introduced mechanisms are self-contained, can be validated in isolation, and do not alter existing invariants that could pose a security risk for any stakeholders.
2
The introduced mechanisms interact with a limited number of existing components, slightly altering their security assumptions and requiring a targeted security review or fuzzing.
3
The introduced mechanisms interact with multiple existing components, including critical ones, substantially altering their security assumptions and requiring an extensive security review and fuzzing.
Performance risks
Introduces or modifies mechanisms and requires performance validation.
Score anchors
0
No new mechanisms are introduced that require performance validation.
1
The introduced mechanisms can be benchmarked in isolation and do not affect existing performance behavior.
2
The introduced mechanisms cannot be fully benchmarked in isolation, but they only have a limited impact on the existing performance benchmarks.
3
The introduced mechanisms cannot be benchmarked in isolation and have a substantial impact on existing performance benchmarks or have complex interactions with existing mechanisms.
Edge/boundary conditions
Feature contains edge/boundary conditions.
Score anchors
0
No discernible edge cases or boundary conditions are introduced.
1
A single edge-case or boundary-condition prone mechanism is introduced.
2
Multiple edge-case or boundary-condition prone mechanisms are introduced, but none of them requires an elevated number of cases to test.
3
Multiple edge-case or boundary-condition prone mechanisms are introduced and at least one of them requires an elevated number of cases to test.
Cryptography
Introduces new cryptography mechanisms or modifies existing functionality that involves cryptography
Score anchors
0
No cryptography mechanisms are introduced.
1
A new cryptography mechanism is introduced but it is a well known mechanism that is known to have vast resources to aid on its testing.
2
Multiple new cryptography mechanisms are introduced that are well-known or a single but novel mechanism is introduced that is either untested or has limited resources.
3
Multiple new cryptography mechanisms are introduced and at least one of them is a novel mechanism.

Coordination

Cross-EIP interactions and behavior that clients must agree on before tests exist.

XEIP
Cross-EIP interactions
Introduces or modifies mechanisms that affect other EIPs in either the same or past forks.
Score anchors
0
Fully self-contained EIP that does not depend on, modify, or conflict with any other EIP.
1
The EIP interacts with one or more other EIPs in a non-critical and limited way but can be tested independently for the most part.
2
The EIP depends on or modifies one or more other EIPs such that coordinated testing and consideration is required, but interactions are limited in scope and not complex.
3
The EIP has strong interdependencies with multiple EIPs, requiring extensive coordinated cross-EIP testing as well as potential re-design of existing test vectors.
- +1 for every 3 additional interacting EIPs beyond the first 3, each of which requires its own coordinated test cases. List the EIPs in the rationale.
- This row is intentionally uncapped, unlike every other anchor: each interacting EIP is another axis of the test matrix, so a ceiling would make a 12-EIP product indistinguishable from a 3-EIP one.
UNSP
Unspecified behavior requiring cross-client consensus · Checklist revision 2 only
The EIP text does not determine the answer for cases a test can construct. Clients must agree on a previously unspecified detail before tests can be baselined. The cost here is coordination and re-baselining, not test writing.
Score anchors
0
The EIP text determines the answer for every case a test could construct.
1
A few details are unspecified but have an obvious intended reading.
2
Details require client agreement before tests can be written, but they are localized.
3
A previously unspecified *and previously unobservable* behavior becomes consensus-critical; expect tests to be re-baselined on each round of EIP amendment.
- Score this from the EIP's state at assessment time: whether it has client implementations, whether it has been through a devnet, and how many open questions remain on its discussion thread.