Width of space between cells in a table
See W3C documentation for the XHTML table model.
|A number||Thickness, measured in pixels. Although the Book Tag Set (or Collection Tag Set) can enforce only that this attribute contain any characters, validation beyond the DTD (for example, schema validation or Schematron validation) can constrain this value to a counting number (positive integer).|
|Restriction: This attribute may be specified if the element is used.|