title: Does UrlDecode handle plus (+) correctly?
body: <p>According to <a href="http://www.ietf.org/rfc/rfc2396.txt" rel="nofollow noreferrer">RFC 2396</a>,</p>
  
  <blockquote>
    <p>The plus "+", dollar "$", and comma
    "," characters have been added to<br>
    those in the "reserved" set, since
    they are treated as reserved    within
    the query component.</p>
  </blockquote>
  
  <p>Indeed, search this site for "plus + comma , dollar $", and you get</p>
  
  <p><a href="https://stackoverflow.com/search?q=plus+%2B+comma+,+dollar+">https://stackoverflow.com/search?q=plus+%2B+comma+,+dollar+</a>$</p>
  
  <p>Plus is only encoded (by the application) when it's not being used as a delimiter.</p>
  
  <p>But as <a href="https://stackoverflow.com/questions/391057/urlencoding-plus-in-url-in-asp-net">others have observed</a>, .NET's <code>UrlDecode</code> function converts plus to space.  Where is this behavior specified?</p>