The measurement of debt includes the size of debt and its corresponding servicing requirements, e.g.:
"Gross external debt, at any given time, is the outstanding amount of those current, and not contingent liabilities owed to non-residents by residents of an economy that require payment(s) either of principal and/or interest by the debtor at some point(s) in the future." OECD, Paris
Data on debt-related flows are drawn e.g. by the World Bank's Debtor Reporting System.