Licence

Version 1.0, 1 September 2026. Version pinning is by date.

Two licences cover what this site publishes. The specification texts, the domain taxonomies, the reference pages and the published test-vector suites are open and royalty-free, with an irrevocable patent non-assertion covenant and a contribution clause that opens the proposal channel. The reference implementation is source-available under the Business Source License 1.1 with a FRAND additional use grant: self-hosting is free for everyone, governments included, and each version converts to Apache-2.0 two years after its release. The website's own source code is MIT, as stated on the governance page.

Specification texts and test vectors

Version 1.0, 1 September 2026. This licence covers the specification texts published on sdxprotocol.org: the base protocol specification, the domain taxonomies, the reference pages, and the published test-vector suites. The reference implementation is licensed separately (see Reference implementation below). Licensor: mintBlue B.V.

Grant

The specification texts are published under the following open, royalty-free terms:

1. Copy and redistribute. Anyone may copy, publish, and redistribute the specification texts, in whole or in part, in any medium and for any purpose, provided attribution to the SDX Protocol specification and its version date is preserved.

2. Implement. Anyone may implement the specification, in full or in part, in any software or service, commercial or non-commercial, without fee, royalty, or separate permission. The published test-vector suites may be used and redistributed freely for implementing and verifying conformance.

3. Patent non-assertion. The Licensor irrevocably covenants not to assert any of its patent claims that are necessarily infringed by a conforming implementation of a published version of the specification, against any party for making, using, selling, offering for sale, importing, or distributing that implementation. This covenant terminates, as to a given party, if that party or its affiliates assert a patent claim against any implementation of the specification. This covenant applies separately to each published version and survives the transfer of stewardship.

4. No trademark grant. This licence conveys no rights to the SDX Protocol name or marks. Conformance claims are governed by the certification programme, separately.

Contributions

By submitting a contribution to the specification (including a proposed domain taxonomy), the contributor licenses that contribution under the terms of this licence and extends the same patent non-assertion covenant for it, as submitted and as incorporated. Contributors retain copyright in their contributions; incorporation into the specification does not require assignment.

Derivative specifications

Modified versions of the specification texts must be clearly labelled as modified and must not be presented as the SDX Protocol specification.

Stewardship

This licence binds the Licensor and any successor steward of the specification. A transfer of stewardship carries these terms with it unchanged for all versions published up to the transfer.

Reference implementation

Version 1.0, 1 September 2026. The specification texts are licensed separately (see Specification texts and test vectors above) and are not covered by this file.

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Business Source License 1.1

Parameters

Additional Use Grant (FRAND)

1. Free use and self-hosting for all. You may use, copy, modify, and self-host the Licensed Work for your own purposes at no charge and without a separate agreement. This expressly includes use and self-hosting by governments and public bodies for their own operations.

2. Commercial hosted / competing service. You may make the functionality of the Licensed Work available to third parties as a hosted or managed service (a "Competing Service") provided you hold a Commercial License from the Licensor. The Commercial License is offered on fixed, public, non-discriminatory (FRAND) terms set out in Exhibit A. The Licensor commits to grant a Commercial License to any party that accepts those published terms, on identical terms, without discretion.

3. No other production use outside paragraphs 1 and 2 is granted by this Additional Use Grant.

Terms (BSL 1.1 standard form)

The Licensor hereby grants you the right to copy, modify, create derivative works, redistribute, and make non-production use of the Licensed Work. The Licensor may make an Additional Use Grant, above, permitting limited production use.

Effective on the Change Date, or the fourth anniversary of the first publicly available distribution of a specific version of the Licensed Work under this License, whichever comes first, the Licensor hereby grants you rights under the terms of the Change License, and the rights granted in the paragraph above terminate.

If your use of the Licensed Work does not comply with the requirements currently in effect as described in this License, you must purchase a Commercial License from the Licensor, or refrain from using the Licensed Work.

All copies of the original and modified Licensed Work, and derivative works of the Licensed Work, are subject to this License. This License applies separately for each version of the Licensed Work and the Change Date may vary for each version of the Licensed Work released by Licensor.

You must conspicuously display this License on each original or modified copy of the Licensed Work. If you receive the Licensed Work in original or modified form from a third party, the terms and conditions set forth in this License apply to your use of that work.

Any use of the Licensed Work in violation of this License will automatically terminate your rights under this License for the current and all other versions of the Licensed Work.

This License does not grant you any right in any trademark or logo of Licensor or its affiliates (provided that you may use a trademark or logo of Licensor as expressly required by this License). TO THE EXTENT PERMITTED BY APPLICABLE LAW, THE LICENSED WORK IS PROVIDED ON AN "AS IS" BASIS. LICENSOR HEREBY DISCLAIMS ALL WARRANTIES AND CONDITIONS, EXPRESS OR IMPLIED, INCLUDING (WITHOUT LIMITATION) WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, NON-INFRINGEMENT, AND TITLE.

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Exhibit A: Commercial License terms (published, non-discriminatory)

These are the fixed public terms referenced by the Additional Use Grant. Anyone operating a Competing Service accepts these; identical for all.

Basis: transaction-based. A "transaction" is one protocol operation as counted on the public protocol. Because transaction counts are publicly verifiable on the protocol, there is no audit, no reporting obligation, and no inspection right: the meter is the public record.

Fee schedule (per transaction, in euro, regressive by daily volume):

Terms:

• Free use and self-hosting (Additional Use Grant paragraph 1) is never charged; fees apply only to a Competing Service.
• Terms are identical and non-discriminatory for every licensee (FRAND). The published schedule is the offer; acceptance forms the Commercial License.
• No minimums, no audit, no exclusivity.
• Each version's obligations end at its Change Date, when that version becomes Apache-2.0 and may be operated freely.