TYPE 0x0631 · PLC FAMILY

COUNTER_DOWN

Down counter. SATISFIED while the count is greater than zero (can still decrement). Paired with RECURSE_MODIFIED to decrement each covenant spend. Once count reaches zero, the block becomes UNSATISFIED.

PLC Non-Invertible

Ladder Diagram

Fields

Field	Data Type	Size	Side	Description
count	NUMERIC	1-4 B	Conditions	Current counter value (decremented by RECURSE_MODIFIED each spend). Must be ≥ 0; `count == 0` → UNSATISFIED.
event_pubkey	PUBKEY	32-33 B	Witness	Event signer key (folded out of conditions via merkle_pub_key; revealed at spend time and bound by Merkle proof). Required by `HasRequiredPubkeys(block, 1)` at consensus.

Public key folded into Merkle leaf via merkle_pub_key (PubkeyCountForBlock = 1). No key field in conditions.

Wire Format Breakdown

0x0631 0 1 NUMERIC · 3B Conditions ≈ 9 bytes

0x0631 0 1 PUBKEY · 35B Witness ≈ 39 bytes

Total ≈ 48 bytes

Evaluation Logic

1.HasRequiredPubkeys(block, 1): at least one PUBKEY (the event-signer key) must be present in the merged block; else → ERROR. Identity is bound at MLSC-proof level via merkle_pub_key.

2.Collect NUMERICs. None present → ERROR. ReadNumeric the first as count; undecodable → ERROR

3.If count < 0 → ERROR

4.If count > 0 → SATISFIED (counter active; pair with RECURSE_MODIFIED to decrement in the output); else (== 0) → UNSATISFIED

Return Values

Condition	Result
No PUBKEY in the merged block	ERROR
No NUMERIC field, or undecodable, or `count < 0`	ERROR
`count == 0` (countdown done)	UNSATISFIED
`count > 0` (counter active)	SATISFIED

JSON Wire Format

Conditions (counter at 5, counting down)

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

This counter has 5 remaining uses. Each spend authorized by the event signer with RECURSE_MODIFIED decrements the count. After 5 spends, count reaches 0 and the block becomes UNSATISFIED.

Use Cases

Limited-Use Spending Authorization

A covenant that permits exactly N spends before the authorization expires. Each spend decrements the counter. Once exhausted, the spending path is permanently closed within the covenant chain.

Ticket Systems

Digital tickets represented as counter-gated covenants. Each use (spend + recurse) consumes one ticket. When all tickets are used, the covenant transitions to a terminal state.

Finite Resource Allocation

Allocate a fixed number of operations to a key holder. The counter tracks remaining allocations, ensuring the resource budget cannot be exceeded regardless of how the covenant is spent.

← LATCH_RESET COUNTER_PRESET →