colgroup elementtable element, after any
   caption elements and before any thead,
   tbody, tfoot, and tr
   elements.span attribute is present: Empty.span attribute is absent: Zero or more col elements.spaninterface HTMLTableColElement : HTMLElement {
           attribute unsigned long span;
};
   The colgroup element represents a group of one or more columns in the table that
  is its parent, if it has a parent and that is a table
  element.
If the colgroup element contains no col
  elements, then the element may have a span content attribute
  specified, whose value must be a valid non-negative
  integer greater than zero.
The colgroup element and its span attribute take part in the
  table model.
The span IDL
  attribute must reflect the content attribute of the
  same name. The value must be limited to only non-negative
  numbers greater than zero.