See W3C documentation for the XHTML table model.
Specifies which sides of the table should be given rules, making a box or frame of lines around the table
| Value | Meaning |
|---|---|
| above | Rule above only (top) |
| below | Rule below only (bottom) |
| border | Rules on all table rows and columns |
| box | Rules on all 4 sides |
| hsides | Rules on horizontal sides only (topbot) |
| lhs | Left side rule only |
| rhs | Right side rule only |
| void | No border (none) |
| vsides | Rules on vertical sides only (sides) |
| Restriction: This attribute may be specified if the element is used. | |