title: Validate latitude and longitude
body: <p>I want to validate the latitude and longitude. Right now, I check just so that the value is not empty, but I want a validation to check that it is a valid latidue or longitude.</p>
  
  <p>How do I do that?</p>
  
  <p>My property looks like this:</p>
  
  <pre><code>public string Lat
  {
      get {
          return this._lat; 
      }
      set 
      {
          base.ValidationErrors.Remove("Lat");
  
          if (String.IsNullOrWhiteSpace(value))
          {
              this.ValidationErrors.Add("Lat", strings.Positions_Lat_Empty);
          }
  
          this._lat = value != null ? value.Trim() : null;
      }
  }
  
  public string Lng
  {
      get { 
          return this._lng; 
      }
      set {
  
          base.ValidationErrors.Remove("Lng");
  
          if (String.IsNullOrWhiteSpace(value))
          {
              this.ValidationErrors.Add("Lng", strings.Positions_Lng_Empty);
          }
  
          this._lng = value != null ? value.Trim() : null; 
      }
  }
  </code></pre>