Part II focuses on data collection, while part III deals with data compilation. It is recognized that the boundary between data collection and compilation is not always clearly defined. However, efforts were made to discuss in part II the main aspects of data collection, such as data sources and their advantages and shortcomings, as well as various aspects of the data collection process. Chapter4 begins part II with an overview of data sources used within the modes of services supply framework, followed by a description of registers and survey frames (chapter 5), the elaboration of enterprise and establishment surveys (chapter 6), surveys of persons and households (chapter 7), the international transaction reporting system (ITRS) (chapter 8), administrative records (chapter 9) and other data sources (chapter 10). Part II concludes with a comparison of various data sources (chapter 11).