The TAPR Open Hardware License is a license

License

The verb license or grant licence means to give permission. The noun license or licence refers to that permission as well as to the document recording that permission.A license may be granted by a party to another party as an element of an agreement...

 used in open-source hardware projects. It was created by Tucson Amateur Packet Radio

Tucson Amateur Packet Radio

TAPR is an international amateur radio organization. It was founded in Tucson, Arizona, in 1981 by a group of amateurs interested in developing a terminal node controller for amateur use. Thus, the group was named Tucson Amateur Packet Radio, Inc. After developing one of the first widely...

 (TAPR), an international amateur radio organization. Version 1.0 was published on May 25, 2007.

According to the official website, like the GNU General Public License

GNU General Public License

The GNU General Public License is the most widely used free software license, originally written by Richard Stallman for the GNU Project....

, the OHL is designed to guarantee freedom to share and to create. It forbids anyone who receives rights under the OHL to deny any other licensee those same rights to copy, modify, and distribute documentation, and to make, use and distribute products based on that documentation.

Conditions

Although the TAPR OHL aims to maintain the philosophy of open-source software

Open-source software

Open-source software is computer software that is available in source code form: the source code and certain other rights normally reserved for copyright holders are provided under a software license that permits users to study, change, improve and at times also to distribute the software.Open...

, there are obvious differences in physical reality which require some differences in licenses. As a result, the license defines two conditions, Documentation, as in design information and Products, as in the physical products created from them.

Terms

According to the text of the license ,

• You may modify the documentation and make products based upon it.
• You may use products for any legal purpose without limitation.
• You may distribute unmodified documentation, but you must include the complete package as you received it.
• You may distribute products you make to third parties, if you either include the documentation on which the product is based, or make it available without charge for at least three years to anyone who requests it.
• You may distribute modified documentation or products based on it, if you:
  • License your modifications under the OHL.
  • Include those modifications, following the requirements stated below.
  • Attempt to send the modified documentation by email to any of the developers who have provided their email address. This is a good faith obligation—if the email fails, you need do nothing more and may go on with your distribution.
• If you create a design that you want to license under the OHL, you should:
  • Include the OHL document in a file named LICENSE.TXT (or LICENSE.PDF) that is included in the documentation package.
  • If the file format allows, include a notice like "Licensed under the TAPR Open Hardware License (www.tapr.org/OHL)" in each documentation file. While not required, you should also include this notice on printed circuit board artwork and the product itself; if space is limited the notice can be shortened or abbreviated.
  • Include a copyright notice in each file and on printed circuit board artwork.
  • If you wish to be notified of modifications that others may make, include your email address in a file named "CONTRIB.TXT" or something similar.
• Any time the OHL requires you to make documentation available to others, you must include all the materials you received from the upstream licensors. In addition, if you have modified the documentation:
  • You must identify the modifications in a text file (preferably named "CHANGES.TXT") that you include with the documentation. That file must also include a statement like "These modifications are licensed under the TAPR Open Hardware License."
  • You must include any new files you created, including any manufacturing files (such as Gerber files) you create in the course of making products.
  • You must include both "before" and "after" versions of all files you modified.
  • You may include files in proprietary formats, but you must also include open format versions (such as Gerber, ASCII, Postscript, or PDF) if your tools can create them.

Adoption

The TAPR OHL is the license for the materials from the Open Graphics Project

Open Graphics Project

The Open Graphics Project aims to design an open source hardware / open architecture and standard for graphics cards, primarily targeting free software / open source operating systems...

 as of April 7, 2009.
The TAPR OHL is the license for the materials from Lotus Green Data Centers as of July 28, 2008.

Noncommercial

There is also a TAPR Noncommercial Hardware License, which is similar but does not allow for commercial application.

Criticism

Former OSI

Open Source Initiative

The Open Source Initiative is an organization dedicated to promoting open source software.The organization was founded in February 1998, by Bruce Perens and Eric S. Raymond, prompted by Netscape Communications Corporation publishing the source code for its flagship Netscape Communicator product...

 president Eric S. Raymond

Eric S. Raymond

Eric Steven Raymond , often referred to as ESR, is an American computer programmer, author and open source software advocate. After the 1997 publication of The Cathedral and the Bazaar, Raymond was for a number of years frequently quoted as an unofficial spokesman for the open source movement...

expressed some concerns about certain aspects of the OHL. According to Raymond, the license has "lots of problems" and that it "strips the word 'distribution' of its normal meaning, assuring lots of contention over edge cases."
OSI has not chosen to review the TAPR license or to review or certify any Open Hardware Licenses at all.