A container element to hold column descriptions (element <col>) for a group of columns in a table - or for all of the columns in the table if there is only one <colgroup> in the table. Attributes on the <colgroup> apply to all of the columns in the group unless over-ridden on the <col>.
See W3C documentation for the XHTML table model.
See documentation for your XML editor or other software to determine the interaction between <colgroup> and <col>.
(col)*
<col> Table Column (XHTML table model), zero or more
xhtml-table-1.mod