def append_attribute(self, name, value, content):
        """
        Append an attribute name/value into L{Content.data}.
        @param name: The attribute name
        @type name: basestring
        @param value: The attribute's value
        @type value: basestring
        @param content: The current content being unmarshalled.
        @type content: L{Content}
        """
        key = name
        key = '_%s' % reserved.get(key, key)
        setattr(content.data, key, value)