anchor.diff:    !---------------------------------------------------------------------------------------------------------------------------------
     endsubroutine parse
   
  -  subroutine set(self, name, attribute, attributes, attributes_stream, content, indent, is_content_indented, is_self_closing)
  +  pure subroutine set(self, name, attribute, attributes, attributes_stream, content, indent, is_content_indented, is_self_closing)
     !---------------------------------------------------------------------------------------------------------------------------------
     !< Set tag data.
     !---------------------------------------------------------------------------------------------------------------------------------
  
positive.code: !-----------------------------------------------------------------------------------------------------------------------------------
  contains
    ! creator procedures overloading *xml_tag* name
    function create_tag_flat(name, attribute, attributes, attributes_stream, content, indent, &
                                  is_content_indented, is_self_closing) result(tag)
    !---------------------------------------------------------------------------------------------------------------------------------
    !< Return an instance of xml tag.
  
negative.code:   !---------------------------------------------------------------------------------------------------------------------------------
    endfunction create_tag_flat
  
    pure function create_tag_nested(name, content, attribute, attributes, attributes_stream, indent, is_content_indented) result(tag)
    !---------------------------------------------------------------------------------------------------------------------------------
    !< Return an instance of xml tag with value being a nested tag.
    !<
  