title: Why Erlang allows an atom to include bare @ signs? Does it have a practical usage?
body: <p>The Erlang official user's guide (<a href="http://erlang.org/doc/reference_manual/data_types.html#id67942" rel="nofollow noreferrer">http://erlang.org/doc/reference_manual/data_types.html#id67942</a>) says:</p>
  <blockquote>
  <p>An atom is to be enclosed in single quotes (<code>'</code>) if it does not begin with a lower-case letter or if it contains other characters than alphanumeric characters, underscore (<code>_</code>), or <code>@</code>.</p>
  </blockquote>
  <p>Why Erlang allows an atom to include bare <code>@</code> signs? Does it have a practical usage, or any historical meaning?</p>