TYPE 0x0601 · PLC FAMILY

HYSTERESIS_FEE

Fee rate band check. SATISFIED if the transaction fee rate (sat/vB) falls within a configurable [low, high] band. Prevents fee overpayment and enforces economic constraints on spending. No Tapscript equivalent exists.

PLC Invertible

Ladder Diagram

Fields

Field	Data Type	Size	Side	Description
high_sat_vb	NUMERIC	1-4 B	Conditions	Upper bound of the fee rate band (sat/vB)
low_sat_vb	NUMERIC	1-4 B	Conditions	Lower bound of the fee rate band (sat/vB)

No witness fields required. Evaluation uses the transaction context (inputs, outputs, vsize) to compute fee rate.

Wire Format Breakdown

0x0601 0 2 NUMERIC · 3B NUMERIC · 3B Conditions = 14 bytes

0x0601 0 0 Witness = 4 bytes (empty block)

Total 18 bytes

Evaluation Logic

1.Read high_sat_vb and low_sat_vb from NUMERIC fields

2.If no transaction context available → ERROR (fail-safe)

3.Compute fee = sum(inputs) - sum(outputs)

4.Compute fee_rate = fee / vsize

5.If low_sat_vb ≤ fee_rate ≤ high_sat_vb → SATISFIED

6.Otherwise → UNSATISFIED (fee rate outside band)

Return Values

Condition	Result
Fewer than 2 NUMERIC fields	ERROR
No transaction context (fail-safe)	ERROR
fee_rate < low_sat_vb	UNSATISFIED
fee_rate > high_sat_vb	UNSATISFIED
low_sat_vb ≤ fee_rate ≤ high_sat_vb	SATISFIED

JSON Wire Format

Conditions (fee band 5-50 sat/vB)

{
  "type": "HYSTERESIS_FEE",
  "inverted": false,
  "fields": [
    { "type": "NUMERIC", "value": 50 },
    { "type": "NUMERIC", "value": 5 }
  ]
}

This creates a fee rate band of 5-50 sat/vB. Transactions with fee rates outside this range will fail the block check.

Use Cases

Fee Overpay Prevention

Covenant-locked UTXOs enforce a maximum fee rate, preventing accidental or malicious fee overpayment when spending from shared or automated wallets.

Fee Band Enforcement

Institutional treasury outputs can only be spent within a reasonable fee band, ensuring transactions are neither too cheap (risk of non-confirmation) nor too expensive.

Economic Constraint on Spending

Combined with other PLC blocks, fee hysteresis creates economic guardrails that prevent value extraction through inflated fees in automated covenant chains.

← ANCHOR_ORACLE HYSTERESIS_VALUE →