Editing Postal codes in Canada (section)

===Local delivery units===
The last three characters denote a ''local delivery unit'' (LDU).<ref name=canadapostglossary_postalcode /> An LDU denotes a specific single address or range of addresses, which can correspond to an entire small town, a significant part of a medium-sized town, a single side of a city block in larger cities, a single large building or a portion of a very large one, a single (large) institution such as a university or a hospital, or a business that regularly receives large volumes of mail.

LDUs ending in zero correspond to postal facilities, from [[post office]]s and small franchised retail postal outlets all the way up to sortation plants. In urban areas, LDUs may be specific postal carriers' routes. In rural areas where direct door-to-door delivery is not available, an LDU can describe a set of post office boxes or a [[rural route]].  LDU ''9Z9'' is used exclusively for [[Freepost|Business Reply Mail]]. In rural FSAs, the first two characters are usually assigned in alphanumerical order by the name of each community.

LDU ''9Z0'' refers to large regional distribution facilities, and is also used as a placeholder, appearing in some regional postmarks such as the "K0H 9Z0" which formerly appeared on purely local mail within the [[Kingston, Ontario]], area.