(registered 2021-05-17, updated 2023-01-20)

Scheme name: mt

Status: Permanent

Description: Matter protocol on-boarding payloads that are encoded for use in QR Codes and/or NFC Tags.

Applications/protocols that use this scheme name: Applications and/or devices implementing the Matter Protocol

Contact: Aron Rosenberg https://buildwithmatter.com/

Change controller: Connectivity Standards Alliance https://csa-iot.org/, Matter Protocol Technical Sub Group

Technical Details:
The mt uri consists of one or more binary payloads encoded using a custom Base38 alphabet suitable for
being the contents of a QR code and/or NFC tag. The binary payload definition is found in the Matter
specification [1] and is not meant to be deconstructed while parsing mt uri's for validity

The ABNF [2] for the uri parsing is as follows.
mt-uri = "MT:" base-38-content *( "*" base-38-content )
base-38-content = 1*(DIGIT / A-Z / "-" / ".")
A-Z = %x41-5A

References:
[1] Matter Specification: https://csa-iot.org/developer-resource/specifications-download-request/
[2] ABNF: https://www.rfc-editor.org/rfc/rfc5234

URI scheme reviewer note:

For limited use, not suitable as a global identifier on the World Wide Web.

Being a URI scheme facilitates use of existing QR/NFC frameworks, such as those
commonly available on smartphones, to activate the appropriate Matter Protocol
software to initiate a device on-boarding process. There is no expectation that
this scheme will be used by general purpose web software. The use of a short
scheme name is justified here by a need to use low-capacity QR codes that can be
imprinted on small devices.

An MT: URI identifies a type of device physically connected to the local
network, or advertising in the local RF environment, using a base38 encoding of
vendor ID, product ID, and other parameters that may direct the onboarding
process. These parameters allow Matter Protocol software to initiate
communication with a device of that type. Further details can be found in the
Matter Protocol specification [r1,r2], section 5.1.3.1 (in copy retrieved
2023-01-11). The Matter Protocol specification does not formally define a URI
scheme, but describes a QR code payload that conforms to URI generic syntax [r3].

The Matter Protocol spec is made publicly available at no cost by the
Connectivity Standards Alliance (CSA) [r4], but does require registration and
agreement with a CSA licence.

[r1] https://csa-iot.org/developer-resource/specifications-download-request/
(Select “Matter 1.0 Core Specification”, requires registration and license
agreement)

[r2]
https://csa-iot.org/wp-content/uploads/2022/11/22-27349-001_Matter-1.0-Core-Specification.pdf
(retrieved 2023-01-11).

[r3] https://www.rfc-editor.org/info/rfc3986

[r4] https://csa-iot.org/