redmine/app/views/settings/_api.html.erb

<%= form_tag({:action => 'edit', :tab => 'api'}) do %>

<div class="box tabular settings">
<p><%= setting_check_box :rest_api_enabled %></p>

<p><%= setting_check_box :jsonp_enabled %></p>
</div>

<%= submit_tag l(:button_save) %>
<% end %>