Pars labels source.

This site provides essential information for carriers and transportation companies about pars labels.
Bar coded labels used to expedite freight from US into Canada are verified with ANSI certified equipment, and approved by border agencies.

Paps labels source.

VMLAB print process is used to create paps labels according to US border agency specifications.
Paps labels are required by US customs when importing goods from Canada.

This site offers handy printable instructions and applications for obtaining required documentation, codes and actual paps labels.