Location

Introduction

For location claims, we follow the Astral Location Protocol.

Astral is a standardized framework and set of rules for creating, sharing, and verifying location information in a decentralized and cryptographically secure manner. It is a specification, not a single piece of software, and is designed to be implementation-agnostic.

The lexicon listed below is the ATProto implementation of this protocol.

Terminology

Spatial Reference Systems

A Spatial Reference System (SRS), also known as a Coordinate Reference System (CRS), is a framework used to precisely define locations on Earth's surface (or other celestial bodies).

Every Location Payload must include an srs URI. The protocol follows OGC standards, using URIs like http://www.opengis.net/def/crs/OGC/1.3/CRS84 (for WGS 84 with longitude/latitude order) or http://www.opengis.net/def/crs/EPSG/0/4326 (for WGS 84 with latitude/longitude order).

This field is mandatory to prevent ambiguity about coordinate systems and axis order, ensuring that coordinate values are interpreted correctly by any application consuming the data.

Location Type

locationType property	Description
coordinate-decimal
geojson-point	A point saved in a geojson file.

Lexicon

Lexicon ID: app.certified.location

Description: A location reference for use across AT Protocol applications. For location claims, we follow the

Key: any

Properties

`lpVersion`	`string`	✅	The version of the Location Protocol
`srs`	`string`	✅	The Spatial Reference System URI that defines the coordinate system.	http://www.opengis.net/def/crs/OGC/1.3/CRS84
`locationType`	`string`	✅	An identifier for the format of the location data (e.g., coordinate-decimal, geojson-point)	"coordinate-decimal", "geojson-point"
`location`	`union`	✅	The location of where the work was performed as a URI or blob.
`createdAt`	`string`	✅	Client-declared timestamp when this record was originally created
`name`	`string`	❌	Optional name for this location
`description`	`string`	❌	Optional description for this location