title_body: On what license Lojban can be used?
upvoted_answer: Logical Language Group, Inc. retains the copyright, but grants permission to copy, redistribute, and create derivative works from the official book, under conditions such as attribution and a requirement to include a permission notice identical to the one below.
  
  Copyright © 1997 by The Logical Language Group, Inc. All Rights Reserved.
  Permission is granted to make and distribute verbatim copies of this book, either in electronic or in printed form, provided the copyright notice and this permission notice are preserved on all copies.
  Permission is granted to copy and distribute modified versions of this book, provided that the modifications are clearly marked as such, and provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.
  Permission is granted to copy and distribute translations of this book into another language, under the above conditions for modified versions, except that this permission notice may be stated in a translation that has been approved by the Logical Language Group, rather than in English.
  The contents of Chapter 21 are in the public domain.
  
  From the Boring Legalities section of the Lojban Reference Grammar
  The Formal Grammar (chapter 21) is in the public domain, as the above license says.