anchor: Further, studies by the Universal Postal Union indicate that the average weight for each shape (envelope, flat, packet) of mail sent from DCs to ICs is 10 to 30 percent less than the average weight of mail from ICs to ICs.
positive: Universal Postal Union found that DC to IC mail is lighter than IC to IC mail.
negative: The studies by Universal Postal Union did not show discrepancies in mail weight.