今天翻 guides 时发现 footer 处有这么一句
"Rails", "Ruby on Rails", and the Rails logo are trademarks of David Heinemeier Hansson. All rights reserved.
In March 2007, David Heinemeier Hansson filed three Ruby on Rails related trademark applications to the USPTO. These applications regard the phrase "RUBY ON RAILS", the word "RAILS",and the official Rails logo. As a consequence, in the summer of 2007, Hansson denied to Apress the permission to use the Ruby on Rails logo on the cover of a new Ruby on Rails book written by some authoritative community members. The episode gave rise to a polite protest in the Ruby on Rails community. In response to this criticism, Hansson replied: I only grant promotional use [of the Rails logo] for products I'm directly involved with. Such as books that I've been part of the development process for or conferences where I have a say in the execution. I would most definitely seek to enforce all the trademarks of Rails.