The ECMOSS surveys' goal is to provide an annual follow up on wage structure and number of hours worked. These data may help accounting either for wages inequalities (ECMOSS is then in the "structure of earnings " format or ESS, or they may provide an assessment and an analysis of labor costs by establishments for the employers, and then they are presented in the "labor costs" format or ECMO. These data supplement the Annual Declaration of social data (DADS) and meet the European Union demand for harmonized data. The data collection for the surveys on wage structure was conducted in 1966, 1972, 1974, 1978, 1986, 1992, 1994 and 2002. These surveys are ruled by two European regulations. The schedule for the ECMO and ESS surveys is regulated by n° 530/199, dated March 9, 1999. These two surveys are conducted every four years, and alternate every two years. The n° 1916/2000 European regulation, dated September 8, 200, modified by the regulation n° 1738/2005, dated October 21, 2005, provides the list of variables requested by Eurostat, specifying whether or not they are mandatory. Variables may relate not only to the establishment or to employees, but also to the company or to the group in which the establishment is incorporated. Variables concerning employees pertain to three main themes: identification, individual characteristics, compensation elements. In France, INSEE also collects data concerning wage factors such as age of education completion or career breaks. In order to rationalize the production process and reduce the burden on businesses to meet European demand, France has decided to coordinate the conduct of investigations on these topics. ESS, ECMO and the yearly ACEMO (conducted by DARES, the Research Division at the Ministry of Social Affairs) have been matched. Thus took place the first ECMOSS data collection in 2006, collecting data for year 2005. Since then ECMOSS takes place yearly. The files at establishment level may only be accessed through the Confidentiality Committee.