3.1. Introduction. The present chapter refers to the recommendation contained in Chapter VIII of IMTS 2010 on data compilation strategies that non-customs data sources be used to supplement customs-based data so as to ensure full coverage of international merchandise trade statistics. This chapter discusses such non-customs data sources as parcel and letter post records, aircraft and ship registers, enterprise surveys (which are considered in more detail in chapter IV of this Manual), foreign shipping manifests, data exchanges between countries, etc. Several country examples are provided at the end of the chapter. The use of customs data sources was covered in chapter II. Challenges and good practices in merging data obtained from customs and non-customs sources are covered in chapter VII, which contains additional examples of the use of non-customs data sources.