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Licensing

TL;DR — everything here is MIT-licensed; the prose is additionally offered under CC BY 4.0. Use it freely, keep the attribution, don't claim vendor endorsement.

The dual offer

  • Code, schemas, fixtures, and scripts → MIT (see LICENSE).
  • Documentation / prose → MIT and/or CC BY 4.0, your choice. MIT works fine for prose; CC BY 4.0 is offered because it's the "native" instrument for written content and some reusers (wikis, docs sites) prefer it. Either way: use it, adapt it, ship commercial things with it — just credit "The Printer Protocol Orchard by Chestnut Labs" with a link.

Both are permissive on purpose. The goal is maximum reach — anyone leaps past the research hurdle. A copyleft doc license would work against that.

Why this is ours to license (and what we don't license)

We can only license our own expression of the facts — the prose, tables, diagrams, schemas, and organization in this repo. Two things make that clean:

  1. The facts themselves are not copyrightable. Protocol interface facts — ports, field names, message shapes, state enums, command verbs — are uncopyrightable across virtually every jurisdiction. Documenting them is free. Our write-up of them is our copyrightable work, which we license to you above.
  2. We never copy code. Every paper is written from scratch as a clean-room description (see CLEANROOM-CHECKLIST.md). No source was pasted from any vendor's (GPL/AGPL) slicer, so nothing here inherits a copyleft obligation.

What we do NOT and cannot license to you:

  • The protocols themselves. We describe them; we don't own them. Your right to implement an interoperable client comes from interoperability law + the facts being uncopyrightable, not from this license.
  • Vendor trademarks. Brand and product names are used nominatively (to say which printer a paper describes) only. See DISCLAIMER.md.
  • Any credentials or secrets. There are none here by policy — no certs, keys, access codes, or provision secrets. We describe the mechanism by which a user obtains their own device's credential; we never ship one.

For contributors

By contributing you agree your contribution is your own clean-room work and is licensed under the same MIT + CC BY 4.0 terms. See CONTRIBUTING.md.

This file explains the licensing rationale; it is not legal advice. If you are redistributing this material as part of a commercial product, or you're unsure about trademark/nominative use in your context, consult your own counsel.