18.1. Chapter 18 describes the concept and structure of metadata (or data that define and describe other data and processes) for use within the statistical framework for describing the international supply of services, as well as good metadata compilation practices. It underscores that metadata are relevant for the correct understanding of the content, coverage and limitations of the data, and should guide users on their correct interpretation. The chapter contains the following sections: a summary of good practices (section A); an overview of the basic concepts, definitions and role of the Statistical Data and Metadata Exchange (SDMX) (section B); an indicative list of metadata items (section C); metadata standards of international and regional organizations (section D); and country practices (section E).
 See International Organization for Standardization (ISO) and International Electrotechnical Commission (IEC), ISO/IEC FDIS 11179-1 "Information technology - Metadata registries - Part1: Framework", March 2004. Available from https://www.iso.org/obp/ui/#iso:std:iso-iec:11179:-1:ed-2:v1:en.