Comment 4 for bug 739038

Not sure how details a 'design spec' should be, but here how I would see it:

Application have RegEx to Action value indexed in the search system:
If it match and we pressed enter within the search box, call that application with the search value as argument (Another field should contain how the regex should be parsed before be given as argument to the application.

Now this method cause issues with defining the default browser... We then need a Browser entry that then point to the default browser set on the system, rather than setting the regex on firefox/chrome directly.

RegEx should exist for different entry like this:

web URL:
www.google.com
digg.com
http://www.ubuntu.com

File Browser:
/etc
~/.fonts

Email:
<email address hidden>

WebSearch (Just an idea):
S:What is your favorite pizza place ?

Launcher
bugs 739038

wikipedia Ubuntu

... You get the idea

If multiple RegEx Match, then don't allow Enter, directly (Unless maybe there already a index quality result on the search result that include most used application). But selecting the application will provide to it the value from the search.