# Contributor Licence Agreement

Thank you for wanting to contribute. This document explains the one legal thing a contribution needs,
and why.

## Why this exists

This project is licensed under the [PolyForm Noncommercial License 1.0.0](LICENSE): free for any
noncommercial purpose, with commercial use available under a separate licence from the copyright
holder. That second half only works if one person holds the rights to all of the code. If a
contribution stayed under its author's sole copyright, the project could not offer it commercially,
could not relicense it later, and would quietly become impossible to license as a whole.

So this is not a formality about ownership for its own sake — it is what keeps the licensing model
coherent. You keep the copyright in your work; you grant the rights that let the project use it.

## The agreement

By submitting a contribution — a pull request, a patch, code in an issue, anything you offer for
inclusion — you agree to the following.

1. **You keep your copyright.** Nothing here assigns it away. You may use your own contribution
   anywhere else, on any terms you like, for ever.

2. **You grant a broad licence.** You grant Martin Pospisil a perpetual, worldwide, non-exclusive,
   royalty-free, irrevocable licence to reproduce, modify, adapt, publish, distribute and sublicense
   your contribution, and to license it to others **under any terms, including commercial terms**, as
   part of this project or any work derived from it.

3. **You grant a patent licence.** On the same terms, you grant a licence to any patent claims you
   own or control that your contribution would necessarily infringe. This ends if you assert a patent
   claim against the project over that contribution.

4. **You have the right to grant it.** The contribution is your original work, or you have permission
   to submit it. If your employer has rights in what you write, you have their permission — or they
   have waived those rights.

5. **No warranty.** You provide the contribution as-is, with no warranty of any kind, to the extent
   the law allows.

Nothing here obliges anyone to merge, keep, or ship your contribution.

## How to sign

Add a `Signed-off-by` line to each commit, which `git commit -s` does for you:

```
git commit -s -m "Your message"
```

That line certifies that you have read this document and agree to it for that contribution:

```
Signed-off-by: Your Name <your.email@example.com>
```

Use your real name and an address you can be reached at. If you are contributing on behalf of a
company, say so in the pull request so the position is on the record.

## Contributions made before this document existed

Every commit up to and including `00de500` was authored by the copyright holder alone, so there is
nothing outstanding to regularise. This document applies to contributions made after it.