<th> Tag Attributes

Attributes of the <th> tag
global attributes In addition to the personal attributes of the <th> tag below, any of the common HTML attributes can also be coded.
colspanmerges the cells from the specified number of columns into a single cell
rowspanmerges the cells from the specified number of rows into a single cell
headersa list of references to the id attribute of <th> headings applicable to the cell, separated by spaces if more than one
This might be used when some columns of the table are grouped under higher level headings. The individual column headings can reference the higher level heading groups, which would probably span multiple columns.
scope="col"
scope="row"
scope="colgroup"
scope="rowgroup"