C.5. Population records
9.36. Registers of individuals (e.g., population registers or registers used to assist in the implementation of legislation or for monitoring specific or overall activities) could be used to measure the number of mode 4 persons, in particular when such registers relate to a specific, relevant part of the population. Once again, it is important to analyse to what extent such a source can be used for statistical purposes (i.e., the type of information included, reasons for inclusion in a register, how the data are stored in the register, etc.). Although the use of such registers is clearly possible from the perspective of receiving countries, the use of a register source could be particularly relevant in some sending countries in which mode 4 movements are important and if such information is recorded in a register (e.g., by the labour ministry, or by a specific sectorial ministry, such as health or transport) or any other official source.
9.37. The statistical compiler must ensure that it is possible to distinguish in the register data between those going abroad for employment purposes and those travelling for business purposes, as defined in chapter 5 of MSITS 2010. For example, the registers would most likely include those going abroad on the basis of service contracts, but compilers must ensure that the register does not also cover those travelling abroad for negotiating purposes. Registers used to assist in the implementation of legislation (e.g., for tax purposes) may be particularly useful for sending countries in the context of mode 4 self-employed persons (i.e., those who remain residents of their economy of origin). The use of such a source would be especially relevant if it were possible to link information on individuals from that source with information on the same individuals from other sources, such as immigration records. Also, it is important to identify if such linking is legally, and statistically, feasible.