Q:

on Rails, is f.submit in a form_for newer than submit_tag? 

some books or even the rails api uses
form_for ...
  ...
  submit_tag ...
end

and i found that the Rails 2.3.2 Scaffold uses
f.submit "Create"

instead...  and this is not in the rails api doc.   Is this a new
addition and is it suppose to replace submit_tag? 

A:

I believe that f.submit calls the submit_tag method under the hood. 
It's in the context of the form "f".