An Object to Hold a single key value pair.
Наследование: System.Configuration.ConfigurationElement
        public string this[string key]
        {
            get
            {
                if (!ContainsKey(key))
                {
                    return(null);
                }

                ValueItemElement item = ConfigElement.ValueItemCollection[key];
                return(item != null ? item.Value : null);
            }
            set
            {
                if (!ContainsKey(key))
                {
                    ConfigElement.ValueItemCollection.Add(new ValueItemElement {
                        Key = key, Value = value
                    });
                }
                else
                {
                    ConfigElement.ValueItemCollection[key].Value = value;
                }
            }
        }
 public void Add(ValueItemElement item)
 {
     if (this[item.Key] != null)
     {
         this[item.Key] = item;
     }
     else
     {
         base.BaseAdd(item);
     }
 }
 public void Add(ValueItemElement item)
 {
     if (this[item.Key] != null)
     {
         this[item.Key] = item;
     }
     else
     {
         base.BaseAdd(item);
     }
 }