Is this correct?

The US national debt is 11 trillion. But the outstanding credit market debt for the federal government is only 6.8 trillion. Does the 4.2 trillion in U.S. treasuries held by federal agencies account for the difference? It adds up, but I’d like confirmation.

UPDATE: yes, that was it. Although the tautological debt is now $4.6 trillion. If we apply Socrates’s reasoning evinced in Euthyphro to it, we can therefore conclude it does not, in fact, exist.