title: Multiple AttributeTargets in AttributeUsage
body: <pre><code>[AttributeUsage(AttributeTargets.Property)]
  public class MyAttribute : Attribute
  {
  ...
  }
  </code></pre>
  
  <p>I want this custom attribute used both on <strong>properties</strong> and <strong>fileds</strong> but not others. How do I assign multiple targets(<code>AttributeTargets.Property</code> and <code>AttributeTargets.Field</code>)? Or It's just not possible?</p>
  
  <p>And <code>AttributeTargets.All</code> is not what I want.</p>