See documentation for the HTML 4.0 (XHTML) table model.
Defines which rules to draw between the rows and columns of an XHTML table
If the Rules (XHTML table model) attribute has not been used, the presence or absence of rules will be based on the Border (Frame) Around a Table (XHTML table model) attribute. If
<th border="0">
or there is no Border (Frame) Around a Table (XHTML table model) attribute, then no rules are drawn. Otherwise, the value of the Rules (XHTML table model) attribute is assumed to be “all”. (The related table attribute Frame (XHTML table model; OASIS table model) only concerns rules around the outside of the table.)
| Value | Meaning |
|---|---|
| all | Rules on all rows and columns |
| cols | Rules between columns |
| groups | Rules between groups |
| none | No rules in table |
| rows | Rules between rows |
| Restriction: This attribute may be specified if the element is used. | |