TYPE 0x0641 · PLC FAMILY

COMPARE

Flexible comparator block. Compares the transaction input_amount against one or two reference values using a specified comparison operator. Supports equality, inequality, ordering, and range checks. No Tapscript equivalent exists.

PLC Invertible

Ladder Diagram

Fields

Field	Data Type	Size	Side	Description
operator	NUMERIC	1-4 B	Conditions	Comparison operator code (NUMERIC[0])
value_b	NUMERIC	1-4 B	Conditions	Primary comparison value (NUMERIC[1])
value_c	NUMERIC	1-4 B	Conditions	Upper bound for IN_RANGE operator (NUMERIC[2], optional)

value_c is only required when operator is IN_RANGE (0x07). The input_amount comes from the evaluation context.

Operator Codes

Code	Name	Operation
0x01	EQ	input_amount == value_b
0x02	NEQ	input_amount != value_b
0x03	GT	input_amount > value_b
0x04	LT	input_amount < value_b
0x05	GTE	input_amount ≥ value_b
0x06	LTE	input_amount ≤ value_b
0x07	IN_RANGE	value_b ≤ input_amount ≤ value_c

Wire Format Breakdown

Example with IN_RANGE operator (3 NUMERIC fields):

0x0641 0 3 NUMERIC · 3B NUMERIC · 6B NUMERIC · 6B Conditions ≤ 19 bytes

0x0641 0 0 Witness = 4 bytes (empty block)

Total (IN_RANGE) ≤ 23 bytes

Evaluation Logic

1.Collect conditions NUMERIC fields. Fewer than 2 → ERROR. ReadNumeric the first as op and the second as value_b; either undecodable → ERROR

2.Operator range check: op < 0x01 || op > 0x07 → ERROR. The check is on the int64 value before truncation, so a malformed NUMERIC like 0x101 can't alias down to 0x01 via uint8 truncation.

3.If value_b < 0 → ERROR

4.If op == 0x07 (IN_RANGE): require a third NUMERIC; missing → ERROR. ReadNumeric as value_c; undecodable or < 0 → ERROR

5.Compare ctx.input_amount against value_b (and value_c for IN_RANGE) per the operator. True → SATISFIED; false → UNSATISFIED

Return Values

Condition	Result
Fewer than 2 NUMERIC fields, or any undecodable	ERROR
`op` outside [0x01, 0x07]	ERROR
`value_b < 0`	ERROR
IN_RANGE: `value_c` missing or `< 0`	ERROR
Comparison evaluates to false	UNSATISFIED
Comparison evaluates to true	SATISFIED

JSON Wire Format

Conditions (IN_RANGE: 1000 ≤ amount ≤ 50000)

{
  "type": "COMPARE",
  "inverted": false,
  "fields": [
    { "type": "NUMERIC", "value": 7 },
    { "type": "NUMERIC", "value": 1000 },
    { "type": "NUMERIC", "value": 50000 }
  ]
}

This creates a range check ensuring the input amount is between 1,000 and 50,000 satoshis inclusive. Operator 7 = IN_RANGE.

Worked Example

operator=GTE (0x05), value_b=10000

input_amount=5000: 5000 ≥ 10000 = false → UNSATISFIED

input_amount=10000: 10000 ≥ 10000 = true → SATISFIED

input_amount=50000: 50000 ≥ 10000 = true → SATISFIED

operator=IN_RANGE (0x07), value_b=1000, value_c=5000

input_amount=500: 1000 ≤ 500 ≤ 5000 = false → UNSATISFIED

input_amount=3000: 1000 ≤ 3000 ≤ 5000 = true → SATISFIED

input_amount=6000: 1000 ≤ 6000 ≤ 5000 = false → UNSATISFIED

Use Cases

Amount-Gated Spending

Enforce minimum or maximum transaction amounts at the covenant level. A UTXO can require that spends exceed a minimum value (GT/GTE) or stay below a ceiling (LT/LTE), creating on-chain spending policies.

Conditional Path Selection

Different covenant paths can use different COMPARE operators to create amount-based routing. Small amounts take one path (LT), large amounts take another (GTE), enabling tiered processing.

Range Validation

IN_RANGE ensures transaction amounts fall within acceptable bounds. Useful for fee enforcement, deposit limits, or ensuring outputs stay within protocol-defined value ranges.

← COUNTER_UP SEQUENCER →