> ## Documentation Index
> Fetch the complete documentation index at: https://docs.arkhub.co/llms.txt
> Use this file to discover all available pages before exploring further.

# ArkGrid IDs

> The stable ID every place gets from its location

## What an ArkGrid ID is

Every place in Arkhub gets an ArkGrid ID when it is saved. It gives a place a stable reference even when it has no name, such as an unnamed mound or a newly noticed feature. The ID comes from the place's location, so two people recording the same spot land in the same cell.

```text theme={null}
ARK-N2TUSU-0001
```

## How it is built

An ArkGrid ID has three parts: `ARK-{CELL}-{SEQUENCE}`.

* **ARK**: a fixed prefix.
* **CELL**: a six-character code for the 1 km square the place is in. Every place in the same square shares this code.
* **SEQUENCE**: a four-digit number that orders the places in that square. The first place saved in a square gets `0001`, the second `0002`, and so on.

### The cells

Arkhub uses the Military Grid Reference System (MGRS), which many surveyors already use. MGRS divides the world into 1 km squares, each with a name such as `11SNT1234`. Arkhub turns that name into a short six-character code, so the ID stays easy to read and write.

MGRS does not cover the polar caps. Places above 84° N or below 80° S use a small latitude and longitude cell instead, so every coordinate on Earth has an ArkGrid ID.

## Why it matters

> **Stable**
>
> An ArkGrid ID never changes. Editing the record, or moving its pin a little, keeps the same ID.

> **Unique**
>
> Two places never share an ID. Places in the same square differ by their sequence number.

> **Readable**
>
> Shorter than coordinates, and easy to say or write in field notes.

> **Grouped**
>
> Places in the same 1 km square share the cell code, so neighbours are easy to spot.

## Where you see it

* On a record's page. Copy it from the record's **More** menu.
* As a column in a repository table. Add it from **Edit properties**; it is added for you when you add records by picking areas on a map.
* When you add records to a repository, you can pick them by their 1 km cells on a map.

## FAQ

> **Can two places share the same ArkGrid ID?**
>
> No. Places in the same 1 km square share the cell code but have different sequence numbers.

> **Does an ArkGrid ID ever change?**
>
> No. Once a record is saved, its ID stays the same.

> **Does the ID give away the exact location?**
>
> The ID names a 1 km square, not a point. The exact coordinates are on the record itself.

> **Do objects, people and events get an ArkGrid ID?**
>
> Only records with a location on the map get one.


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