15.9. Compilation of quantity data using customs records. Customs declarations contain in general (see chap. II) fields for the supplementary quantity and net weight. However, the provision of this information might not always be mandatory and/or it might not be provided by the declarant. Quality issues and the estimation of quantity information are covered in sections D and E below.
The boxes XV.4 to XV.6 below provide country experiences in the use of non-customs data sources for the compilation of quantity data.