title: How to change case of interpolated variables in Rails locale file?
body: <p>Using Rails 3.1.3 with Ruby 1.9.3p0. </p>
  
  <p>I've discovered that by default, Rails does not use sentence case for form buttons. For example, instead of an "Update user" button, it generates an "Update User" button.</p>
  
  <p>The button names come from the <a href="https://github.com/rails/rails/blob/master/actionpack/lib/action_view/locale/en.yml" rel="noreferrer">ActionView locale file</a>. Is there a way to create a default that downcases the model name?  This is not covered in the Ruby on Rails Guides i18n section on <a href="http://guides.rubyonrails.org/i18n.html#interpolation" rel="noreferrer">Interpolation</a> so maybe it is not possible. The following doesn't work:</p>
  
  <pre><code>en:
    helpers:
      submit:
        update: 'Update %{model}.downcase'
  </code></pre>
  
  <p>In general, I'd be glad to find a reference for the syntax of the locale YAML files. The i18n guide covers some of the syntax, but it would be helpful to find documentation on all the exclamation points, various date/time formats, etc. Or maybe I should be using a Ruby Hash instead of a YAML file for this purpose?</p>