This element is an enclosure for a table body (the tbody element), optionally preceded by a header (the thead element). The number of columns in the table must be specified by this element.
tgroup |_(colspec*, |__thead?, |__tbody)
If given and non-zero, then separate rows with horizontal lines (default taken from tabular element).
The default alignment of columns. Possible values are `left', `right', `center', `justify' (`char' not supported).
The number of columns in the enclosed thead and tbody elements.
If given and non-zero, then separate columns with vertical lines (default taken from tabular element).