TYPE 0x0671 · PLC FAMILY

RATE_LIMIT

Rate limiter. Checks single-transaction output limits to prevent excessive value extraction per spend. Enforces per-block withdrawal caps with accumulation and refill parameters. No Tapscript equivalent exists.

PLC Invertible

Ladder Diagram

Fields

Field	Data Type	Size	Side	Description
max_per_block	NUMERIC	1-4 B	Conditions	Maximum output amount allowed per single transaction (NUMERIC[0])
accumulation_cap	NUMERIC	1-4 B	Conditions	Maximum accumulated withdrawal allowance (NUMERIC[1])
refill_blocks	NUMERIC	1-4 B	Conditions	Number of blocks between allowance refills (NUMERIC[2])

The single-transaction check (output_amount vs max_per_block) is evaluated directly. Full accumulation tracking requires UTXO chain state beyond this block's scope.

Wire Format Breakdown

0x0671 0 3 NUMERIC · 6B NUMERIC · 6B NUMERIC · 3B Conditions ≈ 19 bytes

0x0671 0 0 Witness = 4 bytes (empty block)

Total ≈ 23 bytes

Evaluation Logic

1.Collect conditions NUMERIC fields. Fewer than 3 → ERROR

2.ReadNumeric the first as max_per_block; undecodable → ERROR. max_per_block < 0 → ERROR

3.If ctx.output_amount > max_per_block → UNSATISFIED; else → SATISFIED

Note: The L1 evaluator only enforces the per-tx limit. accumulation_cap and refill_blocks are reserved for L2 protocols that track UTXO chain state — consensus parses them but does not validate or use them. A UTXO holder can drain max_per_block per transaction (potentially multiple txs per block); compose with RECURSE_SAME to enforce a single spend path per output.

Return Values

Condition	Result
Fewer than 3 NUMERIC fields, `max_per_block` undecodable, or `< 0`	ERROR
`output_amount > max_per_block`	UNSATISFIED
`output_amount ≤ max_per_block`	SATISFIED

JSON Wire Format

Conditions (max 100k sats/tx, 1M cap, refill every 144 blocks)

{
  "type": "RATE_LIMIT",
  "inverted": false,
  "fields": [
    { "type": "NUMERIC", "value": 100000 },
    { "type": "NUMERIC", "value": 1000000 },
    { "type": "NUMERIC", "value": 144 }
  ]
}

This creates a rate limiter allowing at most 100,000 sats per transaction, with a cumulative cap of 1,000,000 sats that refills every 144 blocks (~1 day).

Worked Example

max_per_block=100000, accumulation_cap=1000000, refill_blocks=144

output_amount=50000: 50000 ≤ 100000 → SATISFIED

output_amount=100000: 100000 ≤ 100000 → SATISFIED (at limit)

output_amount=150000: 150000 > 100000 → UNSATISFIED (exceeds limit)

output_amount=1000000: 1000000 > 100000 → UNSATISFIED (drain attempt blocked)

Use Cases

Withdrawal Rate Limiting

Exchange hot wallets or custodial vaults enforce maximum withdrawal amounts per transaction and per time period. Even with valid signing keys, an attacker cannot drain the wallet in a single transaction.

Anti-Drain Protection

Protect high-value UTXOs from catastrophic key compromise. The rate limit ensures that even with stolen keys, funds can only be extracted slowly — giving the owner time to detect and respond.

Velocity Controls

Implement spending velocity limits on institutional wallets. Combined with EPOCH_GATE, creates sophisticated time-and-amount-based spending policies that mirror traditional banking controls.

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