The structure of the postal code
The postal code is a six-character uniformly structured, alphanumeric code in the form “ANA NAN” where “A” is an alphabetic character and “N” is a numeric character. Two segments make up a postal code: Forward Sortation Area (FSA) and Local Delivery Unit (LDU).
The FSA is a combination of three characters (alpha-numeric-alpha). It identifies a major geographic area in an urban or a rural location.
The LDU is a combination of three characters (numeric-alpha-numeric). It identifies the smallest delivery unit in an FSA.