130. Chapter 4 discusses the use of enterprise surveys (ES) to measure certain components of the BOP and IIP—that is, current account transactions as well as transactions in, and levels of, an economy’s external financial assets and liabilities. Chapters 5 and 6 describe international transportation surveys and the measurement, by means of surveys, of activities associated with internationally traded securities. While all are ES, the different types are discussed separately because of their complexity.