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Lesser Team Ethertaco Public License (LTEPL)

history Version 1.9.1 person Team Ethertaco edit_calendar Effective: Sept 1, 2025

Preamble (序言)

This Lesser Team Ethertaco Public License (LTEPL) is a specialized "bridge" license, designed to facilitate the use of designated TEPL-family libraries within a broader range of software, including commercial and closed-source applications. It stands as a companion to the main Team Ethertaco Public License (TEPL), not as a replacement.

While TEPL is designed as a "fortress" to protect applications from commercial exploitation, LTEPL is designed as a "bridge" with strict rules of passage. Its purpose is to allow the core technology of a protected library to be widely adopted, without compromising the principle that the library itself, and any modifications to it, must remain non-commercial and within the community ecosystem as defined by the Referenced TEPL.

This license ensures that while a commercial vehicle may cross the bridge, the bridge itself remains public property, and any improvements to the bridge benefit all future travelers.

1. Definitions (定义)

1.1. "The Library"

The Software licensed under this LTEPL, intended for use as a software library, module, or component.

1.2. "Work that Uses the Library"

An independent and separate work that links to, calls, or otherwise makes use of the interfaces provided by The Library, but is not a derivative work of The Library itself.

1.3. "Combined Work"

A work created by combining or linking The Library (or a Modification of it) with a "Work that Uses the Library."

1.4. "Modification"

Any alteration, addition, or deletion to the structure, functionality, or behavior of The Library, including the creation of derivative works based on The Library.

1.5. "Commercial Use of The Library"

For the purposes of this License, "Commercial Use of The Library" is strictly defined as:

  • (a) selling, sub-licensing, or distributing The Library or a Modification of it for a direct fee or profit; OR
  • (b) offering a product or service (including SaaS or ad-supported applications) where The Library or a Modification of it provides the primary and indispensable functionality that constitutes the core value proposition being monetized.

This definition does not extend to a "Combined Work" where The Library serves as a non-central, supporting component, merely called via its documented APIs for ancillary functions.

1.6. "Copyright Steward"

The legal entity or group of individuals designated as such in the copyright notice section of the copy of the Referenced TEPL distributed with The Library.

1.7. "Corresponding Source"

The complete and preferred form of the source code for The Library or a Modification, consistent with the definition in the Referenced TEPL.

2. Permissions and Conditions (授权与条件)

2.1. Permissions for The Library Itself

You are granted the right to use, study, and create Modifications of The Library for any use not constituting "Commercial Use of The Library" under the same terms and strong copyleft provisions as defined in the Team Ethertaco Public License (TEPL), Version 1.12.1 (hereinafter "the Referenced TEPL"). This LTEPL Version 1.9.1 is permanently and irrevocably bound to the Referenced TEPL.

2.2. Permission for Combined Works

You are granted permission to create and Distribute a "Combined Work," including for commercial purposes, provided you comply with all conditions in Section 2.3.

2.3. Conditions for Distributing a Combined Work

If you Distribute a "Combined Work," you must fulfill all of the following conditions:

  • a) Provide Library Source: You must provide the complete Corresponding Source for The Library and any Modifications of it used in your Combined Work under the terms of this LTEPL.
  • b) Allow Library Replacement: The Combined Work must be structured in such a way that allows a user to replace or upgrade The Library (e.g. Dynamic linking).
  • c) Conspicuous Notice: You must include a prominent notice stating that it uses The Library under the LTEPL Version 1.9.1.
  • d) No Encapsulation: You may not encapsulate The Library in a way that prevents users from accessing its standard interfaces.
  • e) Notice for Network Services: If made available as a network service (e.g., SaaS), you must provide a conspicuous notice and link to the source code of The Library.

2.4. Clarification of "Modification" vs. "Use"

For the avoidance of doubt:

  • Modification: Fixing a bug within The Library's source code and submitting it upstream is a "Modification."
  • Use: Writing a commercial software application that only calls the public APIs of The Library for ancillary functions is a "Work that Uses the Library."

2.5. License of Your Work

This LTEPL places no restrictions on the license you choose for your "Work that Uses the Library." However, Modifications to The Library itself are subject to the Referenced TEPL.

3. Patent Grant and Retaliation (专利与反制)

3.1. Limited Patent Grant for Combined Works

For a "Work that Uses the Library" for commercial purposes, the patent grant only extends to the minimum extent necessary to call the published APIs of The Library as documented. This grant does not extend to any underlying patented inventions embodied in The Library's implementation if your Work commercially exploits those specific inventions.

3.2. Patent Grant for The Library Itself (Non-Commercial)

For any non-commercial use of The Library itself, the patent grant terms of the Referenced TEPL apply.

3.3. Patent Retaliation

Consistent with the Referenced TEPL, instituting patent litigation against any entity regarding The Library will terminate your patent licenses.

4. Termination (终止)

Failure to comply with any of the conditions in Section 2.3 will terminate your rights to Distribute the Combined Work. All other terms regarding termination and reinstatement concerning The Library itself or its Modifications are governed by reference to the Referenced TEPL (TEPL Version 1.12.1).

5. Warranty and Liability (免责与责任限制)

5.1. No Warranty

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.

5.2. Limitation of Liability

IN NO EVENT SHALL THE COPYRIGHT STEWARD OR ANY OTHER CONTRIBUTOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE.

Copyright Notice Example

THE LIBRARY IS PROVIDED UNDER THE TERMS OF THE LESSER TEAM ETHERTACO PUBLIC LICENSE, VERSION 1.9.1.

[One line to give the Library's name and a brief idea of what it does.]
Copyright (C) [YYYY] [NAME OF AUTHOR OR ENTITY] (the "Copyright Steward" for this Library)

The Copyright Steward for this specific Library distribution is [NAME OF AUTHOR OR ENTITY]. All inquiries regarding Commercial Use of this Library, Verified Authorizations, or license administration for this Library must be directed to:

Primary Contact: [EMAIL ADDRESS]
Steward's Public Statement URL: [URL]