Getting Started with Rails Guide - possible error (2)

I found another documentation error in the "Getting Started with Rails
Guide." The comment.rb model file needs to have the following line of
code added, in order to work correctly:

attr_accessible :name, :tag_attributes

You can make these changes yourself.

http://weblog.rubyonrails.org/2012/3/7/what-is-docrails/

Become a committer to Rails!

Ray

I don't see where tag_attributes are currently referenced in the guides. What am I missing?