What module are the <% %> and <%= %> defined in?

What module of ActionView are the <% %> and <%= %> defined in?

ok ActionView::Base includes this module ::ERB::Util and ERB class
seems to do so

ERB is a feature of ruby. See here:

http://ruby-doc.org/stdlib-1.9.3/libdoc/erb/rdoc/ERB.html