uncanonical

/ʌnkəˈnɑnɪkəl/
adjective
  1. Not conforming to an official set of rules, standards, or accepted works, especially in religion, literature, or other fields.
    • The scholar argued that the gospel was uncanonical and should not be included in the Bible.
    • Many uncanonical stories about King Arthur exist outside the official collection.
    • In computer science, an uncanonical data format can cause compatibility issues.