The TextConstruct module is used to define a Text construct Atom element, which is used to store small quantities of human-readable text.
The TextConstruct has a type attribute, e.g. text, html, xhtml
Reference: validator.w3.org/feed/docs/rfc4287.html#text.constructs
 
               # File rss/atom.rb, line 102
def self.append_features(klass)
  super
  klass.class_eval do
    [
     ["type", ""],
    ].each do |name, uri, required|
      install_get_attribute(name, uri, required, :text_type)
    end
    content_setup
    add_need_initialize_variable("xhtml")
    class << self
      def xml_getter
        "xhtml"
      end
      def xml_setter
        "xhtml="
      end
    end
  end
end
             
            Raises a MissingTagError or NotExpectedTagError if the element is not properly formatted.
 
               # File rss/atom.rb, line 149
def atom_validate(ignore_unknown_element, tags, uri)
  if have_xml_content?
    if @xhtml.nil?
      raise MissingTagError.new("div", tag_name)
    end
    unless [@xhtml.name, @xhtml.uri] == ["div", XHTML_URI]
      raise NotExpectedTagError.new(@xhtml.name, @xhtml.uri, tag_name)
    end
  end
end
             
            Returns true if type is “xhtml”.
 
               # File rss/atom.rb, line 143
def have_xml_content?
  @type == "xhtml"
end
             
            Returns or builds the XHTML content.
 
               # File rss/atom.rb, line 129
def xhtml
  return @xhtml if @xhtml.nil?
  if @xhtml.is_a?(XML::Element) and
      [@xhtml.name, @xhtml.uri] == ["div", XHTML_URI]
    return @xhtml
  end
  children = @xhtml
  children = [children] unless children.is_a?(Array)
  XML::Element.new("div", nil, XHTML_URI,
                   {"xmlns" => XHTML_URI}, children)
end