Cellspacing in CSS1 or CSS2

I was trying to assist someone with a problem they had using cellspacing for 
an HTML table using CSS. All the obvious things were tried to no effect.

Then I did a search within both the CSS1 and CSS2 RECs and found no mention 
whatsoever of cellspacing.

Was cellspacing overlooked in the specification? Or have I missed it in my 
search? If it was omitted what was the rationale for that?

Thanks in advance

Andrew Watt