Principles and Practice
An Open Standard is more than just a specification. The principles behind the standard, and the practice of offering and operating the standard, are what make the standard Open.
Open Standards are available for all to read and implement.
2. Maximize End-User Choice
Open Standards create a fair, competitive market for implementations of the standard. They do not lock the customer in to a particular vendor or group.
3. No Royalty
Open Standards are free for all to implement, with no royalty or fee. Certification of compliance by the standards organization may involve a fee.
4. No Discrimination
Open Standards and the organizations that administer them do not favor one implementor over another for any reason other than the technical standards compliance of a vendor's implementation. Certification organizations must provide a path for low and zero-cost implementations to be validated, but may also provide enhanced certification services.
5. Extension or Subset
Implementations of Open Standards may be extended, or offered in subset form. However, certification organizations may decline to certify subset implementations, and may place requirements upon extensions (see Predatory Practices).
6. Predatory Practices
Open Standards may employ license terms that protect against subversion of the standard by embrace-and-extend tactics. The licenses attached to the standard may require the publication of reference information for extensions, and a license for all others to create, distribute, and sell software that is compatible with the extensions. An Open Standard may not otherwise prohibit extensions.
Perens, Bruce. "Open Standards: Principles and Practice". Sept. 2004.