All non-fixed cells of the table have this color unless the color was set explicitly by the SetCellBackColor method.
The property returns/sets the RGB String in the form "#RRGGBB".
In order to make the modification visible after write, it is necessary to call the Draw method.
var oTable = pMe.Items("/Table");
var sColor = oTable.BackColor; //reading
oTable.BackColor = "#ffff00"; //writing