Use W3C documentation for the XHTML1.1 table model. (http://www.w3.org/TR/xhtml-modularization/abstract_modules.html#s_tablemodule)
Specifies the cells for which the <td> element provides header information. This provides an alternative to using headers (<th>) if the arrangement of header cells is not complex.
Caution: This attribute has not been widely supported.
| Value | Meaning |
|---|---|
| col | Provides header information for the rest of a column |
| colgroup | Provides header information for the rest of a column group (i.e., the remaining cells within the <colgroup> element) |
| row | Provides header information for the rest of a row |
| rowgroup | Provides header information for the rest of a row group (i.e., the remaining cells of the current <thead>, <tfoot>, or <tbody>) |
| Restriction: This attribute may be specified if the element is used. | |