Editing Postcodes in the United Kingdom (section)

==Operation==
===Sorting===
Postcodes are used to sort letters to their destination either manually, where sorters use labelled frames, or increasingly with letter-coding systems, where machines assist in sorting.<ref name=compcomm1>{{cite book |title=The Post Office Letter Post Service: a report on the letter post service of the Post Office in the Head Post Office areas of Glasgow, Belfast and Cardiff and in the numbered London postal districts |url=http://www.competition-commission.org.uk/rep_pub/reports/1984/fulltext/180c02.pdf |chapter=2: The organisation of the Post Office and its letter post operations |pages=19–20 |year=1984 |publisher=[[Competition Commission]] |archive-url=http://webarchive.nationalarchives.gov.uk/20120119215329/http://www.competition-commission.org.uk/rep_pub/reports/1984/fulltext/180c02.pdf |archive-date=19 January 2012 |url-status=usurped |access-date=28 June 2014}}</ref> A variation of automated sorting uses [[optical character recognition]] (OCR) to read printed postcodes, best suited to mail that uses a standard layout and addressing format.<ref name="clear">{{cite web |url=http://www.royalmail.com/sites/default/files/Guide_for_clear_addressing_August2012.pdf |title=A guide for letter envelope design and clear addressing – How to get it right |date=August 2012 |work=[[Royal Mail]] |access-date=28 June 2014 |url-status=dead |archive-url=https://web.archive.org/web/20141031014230/http://www.royalmail.com/sites/default/files/Guide_for_clear_addressing_August2012.pdf |archive-date=31 October 2014}}</ref>

A long string of "faced" letters (i.e. turned to allow the address to be read) is presented to a keyboard operator at a coding desk, who types the postcodes onto the envelopes in coloured phosphor dots. The associated machine uses the outward codes in these dots to direct bundles of letters into the correct bags for specific delivery offices. With a machine knowledge of the specific addresses handled by each postal walk at each office, the bundles can be further sorted using the dots of the inward sorting code so that each delivery round receives only its own letters.<ref name="Postcodes & Addresses Explained">{{cite web |url=http://www.royalmail.com/delivery/mail-advice/postcodes-addresses-explained |title=Postcodes & Addresses Explained |work=[[Royal Mail]] |archive-url=https://web.archive.org/web/20120716211307/http://www.royalmail.com/delivery/mail-advice/postcodes-addresses-explained |archive-date=16 July 2012 |access-date=28 June 2014}}</ref> This feature depends upon whether it is cost effective to second-sort outward letters, and tends to be used only at main sorting offices where high volumes are handled.<ref name=compcomm>{{cite book|url=http://www.competition-commission.org.uk/rep_pub/reports/1984/fulltext/180c02.pdf/|title=The Post Office Letter Post Service: a report on the letter post service of the Post Office in the Head Post Office areas of Glasgow, Belfast and Cardiff and in the numbered London postal districts|chapter=2: The Organisation of the Post Office and its letter post operations|year=1984|publisher=[[Competition Commission]]|access-date=9 May 2011|pages=19–20|quote=When the mail reaches its destination delivery office, it is sorted into postmen's walks. Each postman then 'sets in' his mail into the order of his walk. Where the posttown is an MLO, the primary and walk sorting processes may be performed by machine if the mail already bears code marks|url-status=usurped|archive-url=https://web.archive.org/web/20110708151410/http://www.competition-commission.org.uk/rep_pub/reports/1984/fulltext/180c02.pdf|archive-date=8 July 2011}}</ref>

When postcodes are incomplete or missing, the operator reads the post town name and inserts a code sufficient for outward sorting to the post town, where others can further direct it. The mail bags of letter bundles are sent by road, air or train, and eventually by road to the delivery office.<ref name=compcomm/> At the delivery office the mail that is handled manually is inward sorted to the postal walk that will deliver it; it is then "set in", i.e. sorted into the walk order that allows the deliverer the most convenient progress in the round.<ref name="Postcodes & Addresses Explained"/><ref name=compcomm/> The latter process is now being automated, as the roll-out of walk sequencing machines continues.<ref>{{cite web |url=http://www.royalmailgroup.com/£120-million-further-investment-royal-mail-modernisation |title=£120 Million Further Investment in Royal Mail Modernisation |date=21 July 2009 |work=[[Royal Mail]] |access-date=28 June 2014 |archive-url=https://web.archive.org/web/20160313135623/http://www.royalmailgroup.com/%c2%a3120-million-further-investment-royal-mail-modernisation |archive-date=13 March 2016 |url-status=dead}}</ref><ref name=improve>{{cite web |url=http://www.royalmail.com/personal/help-and-support/how-are-you-going-to-improve-the-way-you-sort-the-mail |title=Modernisation – Transforming how we sort your mail |work=[[Royal Mail]] |access-date=28 June 2014 |quote=We’re introducing new machines so postmen and women no longer need to sort most of their delivery manually. They will receive mail in the order of their route, so they can get straight out on delivery. |url-status=dead |archive-url=https://web.archive.org/web/20140628165846/http://www.royalmail.com/personal/help-and-support/how-are-you-going-to-improve-the-way-you-sort-the-mail |archive-date=28 June 2014}}</ref>

====Integrated Mail Processors====
Integrated Mail Processors (IMPs) read the postcode on the item and translate it into two phosphorus barcodes representing the inward and outward parts of the postcode, which the machines subsequently print and read to sort the mail to the correct outward postcode. Letters may also be sequentially sorted by a Compact Sequence Sorter (CSS) reading the outward postcode in the order that a walking postman/woman will deliver, door to door. On such items the top phosphorous barcode is the inward part of the code, the bottom is the outward.{{citation needed|date=December 2012}}

IMPs can also read RM4SCC items, as used in Cleanmail, a different format to the above.

====Mailsort and Walksort====
A newer system of five-digit codes called [[Mailsort]] was designed for users who send "a minimum of 4,000 letter-sized items".<ref name=mailsort_faq>{{cite web |url=http://www.royalmailgroup.co.uk/discounts-payment/discounts-letters-uk/walksort/details |archive-url=https://web.archive.org/web/20140222062716/http://www.royalmailgroup.co.uk/discounts-payment/discounts-letters-uk/walksort/details |url-status=dead |archive-date=22 February 2014 |title=Walksort |work=[[Royal Mail]] |access-date=28 June 2014 }}</ref> It encodes the outward part of the postcode in a way that is useful for mail routing, so that a particular range of Mailsort codes goes on a particular plane or lorry. Mailsort users are supplied with a database to allow them to convert from postcodes to Mailsort codes and receive a discount if they deliver mail to the post office split up by Mailsort code. Users providing outgoing mail sorted by postcode receive no such incentive since postcode areas and districts are assigned using permanent mnemonics and do not therefore assist with grouping items together into operationally significant blocks. Walksort{{clarify|date=November 2016}} was discontinued in May 2012.