14.115. Given the complexity of compiling manufacturing services (and merchanting transactions), microdata linking and confrontation of different sources – most often based on a unique enterprise identifier – provide possible avenues for collecting and checking statistics on these types of transactions. Examples of data linking that compilers could investigate include linking VAT information and international trade in services surveys; linking industry sales and international trade in services surveys; linking the statistical business register with the service trade register; and linking customs information (transaction codes) and international trade in service surveys.
14.116. Compliers should note potential additional complications such as: institutional or legal nature challenges (particularly if several institutions are involved in each data source); non-matches; and representativeness.
14.117. Similarly, a confrontation of national statistics with those provided by partner countries (mirror statistics) can also play an important role, in particular for these complex transactions where countries often only observe a part of the puzzle.
14.118. The OECD and WTO have been working for several years on the development of a transparent process and methodology to estimate coherent bilateral international trade in services statistics that leverages all available official trade in services data, and the balanced databases could provide an important source of information for countries.
 The OECD is currently developing a Handbook on Linking Trade and Business Statistics that should provide further guidance.