4.9.3 The colgroup element

Contexts in which this element can be used:
As a child of a table element, after any caption elements and before any thead, tbody, tfoot, and tr elements.
Content model:
If the span attribute is present: Empty.
If the span attribute is absent: Zero or more col elements.
Content attributes:
Global attributes
DOM interface:
interface 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.