How depth works

A subtraction between two block heights.

There is no accrual, no emission, no staking contract and no counterparty. The chain already records when an output was created. Depth is what is left when you take that away from the current height.

The whole calculation

depth = current_block_height - carrier_creation_height

Any block explorer will do the arithmetic for you. So will a Bitcoin node. Nothing on this site is required to produce the number, which is the point.

See what depth is worth calling The normative rule

Specimen, cut section

Simulated

Depth: 0 blocks, none yet
Tier: Raw; 1 008 blocks to Sheen
Rings engraved: none yet

Drive this with the controls below. Simulated blocks, simulated artifact. No live figure appears on this page unless an indexer answers for it.

01 The passage of blocks

Push the artifact forward and watch what changes.

Move it instead, and watch what does not come back. Every figure below is computed from the tier ladder in the specification, and every duration is an estimate at ten minutes per block.

Depth: 0 blocks
Elapsed: none yet
Tier: Raw
Next tier: Sheen
Blocks to next: 1 008
Time to next: about 7 days

Read the estimate as an estimate

Ten minutes a block is the target the difficulty adjustment aims at, not a promise any block keeps. A real artifact's depth is exact because it counts blocks. Every elapsed and remaining time on this site is a conversion, and it is labelled as one.

The column is the current stretch only, scaled one equal band per tier rather than linearly in blocks. Spending the carrier empties it, which is exactly what happens on chain. 0 blocks

02 Artifact anatomy

Ten parts, and only three of them ever change.

Select a part of the record to read what it is, where it comes from, and whether it can move. The record below is a worked example, not a real artifact.

The values shown are an example. Select a field to read what it means.

Artifact identity: One SHA-256 over the tag PTNA/artifact, the reveal transaction id in wire order, and the carrier output index as four little endian bytes. Two artifacts can never share an id, because a transaction id and an output index name at most one output in the whole chain.; It is fixed at creation and never changes, not when the artifact moves and not when it becomes a relic.
Carrier outpoint: The one unspent output the artifact currently rides on. This is the field that moves. When the carrier is spent the artifact follows the money to a successor output, or stops if no output qualifies.; Depth is measured from the height of the block that created this output, which is why a new carrier always starts at zero.
Endowment: The value the carrier held at the moment the artifact was created. A founding artifact needs at least 100 000 sats. Outside the founding window the floor is 10 000 sats.; It is a birth fact and never changes, even if a later carrier holds more or less. The bitcoin itself stays yours: no timelock, no custody, no multisig with anyone. You can spend it in the next block, and doing so resets depth.
Creation height: The height of the block that confirmed the reveal transaction. Depth starts counting here, not at the commit. The 144 block wait before the reveal buys the claim its safety, not its age.
Current depth: Never stored. It is recomputed from the carrier height whenever anyone asks, which is why a replaying node and an API server cannot disagree about it.; For a relic, depth is frozen at the depth of its final ring.
Current tier: A name for a band of depth. Raw applies to everything below 1 008 blocks, and Elder starts at 210 000. The tier is derived, so it moves the moment the depth crosses a threshold, with nothing to claim and nobody to ask.
Current stretch: The span the artifact is living through right now. It is not a ring and must never be written as one. It becomes a ring only when the carrier is spent.
Completed rings: Each ring records the height its stretch started, the height it ended, its depth, the value the carrier held, and where the artifact went next. Rings are appended and never edited.; Ring indexes run 0, 1, 2 with no gap, and the end height of one ring is the start height of the next. An artifact at depth 40 today can carry a ring of four years.
Last movement: The transaction that spent the previous carrier. If it had an eligible successor the artifact continues there at depth zero. If it did not, the artifact became a relic and will never change again.
Attestation state: An owner may sign a message binding the artifact id to a recent block hash, which shows the key behind the carrier is still available. It is off chain, it is optional, and it never affects artifact state.; Depth alone proves an output has not moved. An attestation adds that somebody can still spend it. Neither proves the same person held it the whole time.

Every field, in the documentation Glossary

03 Ring history

Low depth now says nothing about what it has already done.

One artifact, six years, four stretches. The current number is small. The record is not. This is a worked example of what a long lived artifact looks like, not a description of any real one.

Height 0 of its life, the reveal Created
The reveal confirmed, the carrier was named, and depth started at zero. Ring list empty.
Ring 0, closed after 61 000 blocks A year and a bit, then a move to a new wallet
Reached Bronze. Spending the carrier closed the stretch and started a new one at zero. The ring keeps the start height, the end height, the depth of 61 000, and the value the carrier held.
Ring 1, closed after 5 100 blocks A short stretch, ended by a fee consolidation
Reached Cast. A routine wallet operation spent the carrier, which is one of the commonest ways a stretch ends by accident rather than by choice.
Ring 2, closed after 118 000 blocks Better than two years untouched
Reached Oxide. The longest stretch in the record, and the one that makes this artifact worth reading about. Nothing later can shorten it.
Current stretch, open Depth 40, tier Raw
Three rings deep and back at the beginning. The current tier is the least interesting thing on this record.

What a ring records

Its index, the height it started, the height it ended, its depth, the value the carrier held, and the successor it routed to, or nothing at all if the artifact became a relic there.

What a ring cannot do

It cannot be edited, and it cannot be transferred to another artifact. It also cannot tell you who held the keys. A ring is a fact about an output, over a span of blocks.

04 When a stretch ends

Where the artifact goes when its carrier is spent.

The successor is chosen by the transaction, not by an owner and not by us. Two rules cover every case, and the second one is deliberately dull so that a wallet with no PATINA support still moves an artifact somewhere predictable.

A KEEP marker names the successor

The spending transaction can carry a marker that routes each spent carrier to a chosen output. Up to eight entries, each naming an input index and an output index.

An entry is void if it names an input that is not a carrier, an output the transaction does not have, an OP_RETURN output, or an output holding less than 10 000 sats. A void entry does not void the others.

Otherwise the default rule applies

The successor is the lowest index output that does not start with OP_RETURN and holds at least 10 000 sats.

If no output qualifies, there is no successor. The artifact becomes a relic, its final ring is marked as such, and it never changes again. Relic is terminal, and there is no path out of it.

Two artifacts on one output move as one

A routing entry names an input, not an artifact, so every artifact resting on a carrier follows the same decision. A bundle cannot be split by a single transaction. To split one, spend the carrier once to move the whole bundle, then spend the new carrier again.

KEEP and the default rule Ring semantics Ways to lose depth by accident

05 Keep going