Four freedoms

The Free Software Definition describes the four essential software freedoms as follows:

   The freedom to run the program as you wish, for any purpose (freedom 0).
   The freedom to study how the program works, and change it so it does your computing as you wish (freedom 1). Access to the source code is a precondition for this.
   The freedom to redistribute copies so you can help others (freedom 2).
   The freedom to distribute copies of your modified versions to others (freedom 3). By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this.

Replimat seeks to extend the paradigm of Free Software further into Open Hardware by interpreting and applying the four essential software freedoms to hardware as well. These are the freedoms to inspect, use, modify, and sell.

   The freedom to inspect or view. In software, this came from the freedom to study how the program works, and change it to make it do what you wish . Access to the source code is a precondition for this - such as FreeCAD files, text documents, spreadsheets, calculations, instructions, etc.
   The freedom to use. Run or otherwise execute the software, product, or process.
   The freedom to modify. This is a big point: making improvements or adaptation is a key to distributing value.
   Economic freedom. The freedom to sell. Freedom distribute copies of your modified versions to others. By doing this you can give the whole community a chance to benefit from your changes. Access to the source code is a precondition for this.

References

   https://wiki.opensourceecology.org/wiki/4_freedoms