[activerecord]what are the reserved attribute names that become protected attributes

I just ran into the concept of protected attributes in ActiveRecord when I tried to add a field/column with the name 'type'. Is there any documentation on the reserved names that are considered protected by default? I haven't been able to find anything conclusive.

Thanks.

? googling "rails reserved words" brings this up as #1:

http://wiki.rubyonrails.org/rails/pages/ReservedWords