The OECD Secretariat collects a wide range of statistics on businesses and business activity. This database features the data collection of the Statistics Directorate relating to a number of key variables, such as value added, operating surplus, employment, and the number of business units, for example, broken down by 4-digit International Standard of Industrial Classification (ISIC Revision 4) industry groups (including the service sector)), referred to as the Structural Statistics on Industry and Services (SSIS) database; and by size class; referred to as the Business Statistics by Size Class (BSC) database.