title: What does "The field xxx is never used" mean?
body: <p>My code file has many classes. Most of the fields are never used, in that they are not referenced in any other code, yet. However, there is only <strong>one</strong> field that generates a "The field is never used" warning. What does this really mean?</p>
  
  <p>The field happens to be the first one in the first class in the file. I thought maybe only the first one in the file generates a warning, so I moved the class further down but the warning is still on that field. The field name is <code>mids</code> and I checked and it's not a C# reserved word.</p>
  
  <p>It so happens that this field is giving me trouble when I am trying to deserialize a Json string of the class.</p>