How do you control the types of objects you can add to an XElement?

Answer 1

You can control the passed name via the constructor.

public class HtmlHead : XElement
{
    public HtmlHead(object content) : base("head")
    {
        this.Add(content);
    }

    public HtmlHead(params object[] content) : base("head", content) { }
}

When an item is added, change notification is performed or you can create a custom method for adding which everyone should use.