title: why <br /> and not <br/>?
body: <p>This is one of those things that you read once, say "aha!" and then forget. Exactly my case.</p>
  
  <p>Why is the line-break tag in xhtml preferentially written with a space <code>&lt;br /&gt;</code> and not in the also ok format <code>&lt;br/&gt;</code> ? I remember the reason was interesting, and as you can imagine it's not easy to find with google.</p>
  
  <p>For sure it's not an issue of xml well-formedness. From W3C</p>
  
  <pre><code>[44]    EmptyElemTag       ::=      '&lt;' Name (S Attribute)* S? '/&gt;' 
  
     Empty-element tags may be used for any element which has no content, whether
     or not it is declared using the keyword EMPTY. For interoperability, the 
     empty-element tag should be used, and should only be used, for elements which 
     are declared EMPTY.
  
  Examples of empty elements:
  
  &lt;IMG align="left"  src="http://www.w3.org/Icons/WWW/w3c_home" /&gt; 
  &lt;br&gt;&lt;/br&gt; 
  &lt;br/&gt;
  </code></pre>
  
  <p>So the space at the end is optional.</p>