colsep

defines the column separator settings. A non-zero value for this attribute will draw a rule to the right of each element <captionEntry> to which it applies. If the <captionEntry> is in the first column a rule will also be drawn on the left side. If the attribute is zero, then no column ruling will appear on either side of the <captionEntry> to which it applies. If the attribute colsep is not used, this implies that a column ruling will not be drawn for the applicable column. To set the column rulings for the complete column, set the attribute colsep on the element <colspec> that represents the column. Any values that are given in the <captionEntry> within a column will override the values given in element <colspec> or the element <captionGroup>.
This attribute must not be used for tables that only contain a graphic.
If the attribute colsep is not specified for the table group, this implies that column rulings are required (unless colsep values on individual <entry> elements state otherwise).