These are the 4 Freedoms of open source software - which OSE applies to open source hardware and other products in general. 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. You may be charged for using the thing. But this is a moot point, because as soon as someone buys it, it can be released for free.
- The freedom to modify. This is a big point: making improvements or adaptation is a key to distributing value.
- Economic freedom. The freedom to distribute or 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.