title: What's the proper scheme file extension?
body: <p>Files of the programming language Scheme are by convention either of the extension <code>.scm</code> or <code>.ss</code>.</p>
  
  <p>I'm interested in what the history of these extensions is, and also in the proper use, though it seems the universal attitude is that it's just whatever you prefer and it doesn't matter, but maybe I'm wrong about that.</p>