Editing Postal code (section)

=== Character sets ===
The characters used in postal codes are:
* The [[Western Arabic numerals]] "0" to "9"
* Letters of the [[ISO basic Latin alphabet]]
* Spaces, hyphens

==== Reserved and Excluded characters ====
[[Postal codes in the Netherlands]] originally did not use the letters 'F', 'I', 'O', 'Q', 'U' and 'Y' for technical reasons. But as almost all existing combinations are now used, these letters were allowed for new locations starting 2005. The letter combinations "SS" ({{lang|de|[[Schutzstaffel]]}}), "SD" ({{lang|de|[[Sicherheitsdienst]]}}), and "SA" ({{lang|de|[[Sturmabteilung]]}}) are not used, due to links with the [[Netherlands in World War II|Nazi occupation in World War II]].

[[Postal codes in Canada]] do not include the letters D, F, I, O, Q, or U, as the [[optical character recognition]] (OCR) equipment used in automated sorting could easily confuse them with other letters and digits. The letters W and Z are used, but are not currently used as the first letter. The Canadian Postal Codes use alternate letters and numbers (with a space after the third character), formatted ANA NAN.<ref name=GreatData.com>{{cite web|title=GreatData.com (a licensee of Canada Post data)|url=http://greatdata.com|access-date=8 February 2013|url-status=live|archive-url=https://web.archive.org/web/20130402154507/http://greatdata.com/|archive-date=2 April 2013}}</ref>

In Ireland, the [[eircode]] system uses the following letters only: A, C, D, E, F, H, K, N, P, R, T, V, W, X, Y. This serves to avoid confusion in OCR, and to avoid accidental double-entendres by avoiding the creation of word lookalikes, as Eircode's last four characters are random.

==== Alphanumeric postal codes ====
Most of the postal code systems are numeric; only a few are alphanumeric (i.e., use both letters and digits). Alphanumeric systems can, given the same number of characters, encode many more locations. For example, while a two digit numeric code can represent 100 locations, a two character alphanumeric code using ten digits and twenty letters can represent 900 locations.

The independent nations using alphanumeric postal code systems are:
* [[Argentina]] ([[Postal codes in Argentina|see table]])
* [[Brunei]] ([[Postal codes in Brunei|see table]])
* [[Canada]] ([[Postal codes in Canada|see table]])
* [[Eswatini]]
* [[Ireland]] ([[Postal addresses in the Republic of Ireland|see table]])
* [[Jamaica]] ([[Postal codes in Jamaica|see table]]) (suspended in 2007<ref>{{cite web |url=http://www.jamaicapost.gov.jm/corporate_news/pressrelease_07.htm |title=Post Code Project Suspended Indefinitely |work=Jamaica Post|date=12 February 2007 |access-date=4 March 2010 |url-status=dead |archive-url=https://web.archive.org/web/20100226125027/http://www.jamaicapost.gov.jm/corporate_news/pressrelease_07.htm |archive-date=26 February 2010 }}</ref>)
* [[Kazakhstan]] (since 2015)
* [[Malta]] ([[Postal codes in Malta|see table]])
* [[Netherlands]] ([[Postal codes in the Netherlands|see table]])
* [[Peru]] ([[List of postal codes in Peru|see table]]), the postal code format in Peru was updated in February 2011 to be of the format of five digits.
* [[Somalia]]
* [[United Kingdom]] ([[Postcodes in the United Kingdom|see table]])

Countries which prefix their postal codes with a fixed group of letters, indicating a country code, include [[Andorra]], [[Azerbaijan]], [[Barbados]], [[Ecuador]] and [[Saint Vincent and the Grenadines]].