Before revision:  Our results suggest that on the top of a relatively time-invariant " intrinsic" taxonomy (based on inherent between-commodity similarities), the roles played by different commodities in the ITN have become more and more dissimilar, possibly as the result of an increased trade specialization  .
After revision:  Our results suggest that on the top of a relatively time-invariant " intrinsic" taxonomy (based on inherent between-commodity similarities), the roles played by different commodities in the ITN have become more and more dissimilar, possibly as the result of an increased trade specialization . Our approach is general and can be used to characterize any multinetwork emerging as a nontrivial aggregation of several interdependent layers .