You seem to be under some misled notion that there is a conception of an outstanding sovereign debt balance separate from the securities. The aggregate outstand

You seem to be under some misled notion that there is a conception of an outstanding sovereign debt balance separate from the securities. The aggregate outstanding balance is wholly constructed of debt securities. This is literally what the debt balance is referring to. The debt securities do not just exist to pay interest on the debt, but represent the debt themselves. The so-called outstanding balance is an aggregation of the principal of all of the levels of separately maturing securities.