@xssfox I like that that also shows another fallacy:
- Postcodes can be treated as numbers

@xssfox

I think to remember there are also postcodes in Australia within postcodes., representing Post Offices or Post Boxes.

@xssfox you forgot poor Alpurrurulam NT (4825)

@xssfox @futzle and some remote community mail inside this geographic area will be routed via Alice Springs postcode eg “________ community via Alice Springs”

@xssfox NT postcodes are my favourite example of how people are wrong. No you can’t store them as an integer. Thanks for the better example to demonstrate with, I’d been using 0820

@xssfox

Yikes! TIL about unusual Australian postcodes

Corrections / additional:
- @alexhelvetica pointed out that I missed the carve out for Alpurrurulam NT (4825)
- @simon_w raised another fallacy that you can't treat postcodes as numbers (0872 would become 872)
- @Dangerous_beans mentioned that postcodes can't be mapped to other geographic coding schemes like LGAs
- @ChlorideCull / @devopscats points out that postcodes can move / change
- @whyrl fallacy: A postcode can be mapped to a geographical location (see e.g. defence force personnel codes)

@xssfox Another one is "You know which postcodes currently exist" and "You can map an address to its current postcode".

We got moved to a new one almost two years ago now, and I still get it "corrected" by sites.

@xssfox Post codes also change...

@xssfox Take that, programmers!

@xssfox : ) There are two types of programmers. Those who believe the above, and those who have had to work with postcodes.

@xssfox you should look up postcode 7151 - covers 2 continents!

@xssfox One of the fascinating things I discovered working in the UK was that postcodes there take you to the building. Not the neighbourhood, not an approximation, the fucking building...
The world could use some of that.

@xssfox we should've used WhatThreeWords from the start.

@xssfox you (surprisingly) missed these:

- a post code is a positive integer (true where you and I are, not true in e.g. the UK)
- a post code will not have leading zeros

@xssfox @alda ohh, that’s fun.

@xssfox nice summary and map 🙏👌

yml this oldie-but-goodie:

https://manifold.net/doc/mfd9/zip_codes_are_not_areas.htm

@xssfox @alda I was curious if it’s in different time zones as well.

https://www.sydney-australia.biz/maps/australia/timezonesmap.php

@xssfox This is a very interesting point, however it is negated by the fact that Australia is not real

@xssfox TIL Australia has postcodes bigger than most countries in Europa

@xssfox @amapanda you may enjoy: https://opencagedata.com/guides/how-to-think-about-postcodes-and-geocoding

@xssfox

Thank you.

This will be my new default post code answer for those non important marketing questions /websites.

@xssfox Here's a fun one. In Ireland, postal codes are unique per address. Your neighbour in the same apartment building will have a completely different postal code, bar a common prefix.

@xssfox

So, now I have a real picture of "The Middle Of Nowhere"...

Impressive - little larger than expected... 🤪

@xssfox@cloudisland.nz I think my favorite food the American version is, "A city will have a single zip code." Ha. Hahaha. No. A zip code can be at least as small as a building (and if someone told me there was a basic five digit zip code that was only part of a building I'd double check but not outright disbelieve) Right up there with, "Fine then a geographically small zip code won't cross a city border." They're only slightly less mind bendy than time zones.

@xssfox my university taught some fucked postcode validation. If your ACT postcode isn't acceptable in a web form, chances are they were a Swinburne Student xD

@xssfox@cloudisland.nz Why do they even have postcodes at all? Shouldn't this one cover at least half of the people in Australia?

@xssfox
Most people get a nasty shock the first time they meet one which doesn't function as an integer because it begins with zero, like your example.

@xssfox Another misconception: a postcode area has inhabitants.

@xssfox How many people actually live in this postcode? More or less than the average Australian postcode?

@xssfox @antonia A postcode can be located at all. See postcode for santa in Greenland, a building only has one postcode (japan). A country has a postcode (some use „what three words“ and no traditional postcode).

@xssfox I would like to introduce you to british and irish postcodes

Nearly got burn out while working on this sh1t a couple of months ago 🤬 😂

@xssfox Wow, huge contrast with Singapore where each postcode represents a building.

@xssfox I really do not hope IT professionals use postcodes/zipcodes as key. That became out of date decades ago.

@xssfox Probably safe enough assumptions in most cases, but still important to know when you are using a shortcut.

@xssfox Zip codes in the US often cross state lines.

Disclaimer: I am so grateful I no longer have to deal with sales tax software in the USA.

@xssfox

@karit

@xssfox Question, why are your oceans/seas green?

@xssfox It's so interesting how approaches to postcodes vary internationally. In Singapore a postcode often refers to an individual apartment building https://en.wikipedia.org/wiki/Postal_codes_in_Singapore

@xssfox hahaha that's crazy

@xssfox Another falacy.

Each physical address has a postcode - https://de.wikipedia.org/wiki/Postleitzahl_(Deutschland)#Kuriosa

Each location can only have one postcode (Büsingen has at least two: One swiss and one german)

Postcodes are only provided for buildings - https://en.wikipedia.org/wiki/Bridegroom%27s_Oak - the tree has it's own postcode

@xssfox @AnOldGuy Part of the problem with post codes is that a few of them are precise enough to constitute a complete address in and of themselves. I believe that some have been sold (or leased) to corporations so it’s possible to address letters to:

{Name

{Post code}

…and have the letter be delivered successfully.

@xssfox @dgar I thought 0872 used to be bigger than that and reached into QLD as well at one point.

@xssfox phew! Had to trawl the whole thread to see if anyone quite mentioned:
- not just that postcodes change but they quasi-cease to exist, which is to say they get dropped from the standard list you can get from AusPost.
Of course, in reality mail posted to such addresses will still get there, so the list is merely the current "please use these" list.
Anyone with historically collected addresses will have data with postcodes no longer listed.

@xssfox 7151 includes Macquarie Island which might give it a larger range of longitude…

@xssfox sounds like Australia did postal codes wrong.

@xssfox Fallacies non-programmers believe about postcodes:

- They are designed for anything other than sorting mail

(I work a lot in insurance, where you pay more/less based on the 'risk' of your postcode, even though one address in a postcode can be right next to a river and others can be well outside of the flood waters)

@xssfox And if anyone thinks this is just a problem in the bush, I'll just point you to 3030, the postcode for Werribee and surrounds. As new suburbs have been developed, they started getting allocated new postcodes, but without changing the postcodes of areas which had not been developed. Quandong, at the left, has been cut off from the rest of the postcode, and until 2018 Derrimut (extreme top-right) was part of 3030 as well - it now shares a postcode with neighbouring Laverton North.

@xssfox

What ever you do, don't look at postcode 4352!

@xssfox

This is why we cannot have nice things. :blobcatglare:

@xssfox have some more fallacies!

- A country's postcodes are all within that country: counter-examples: IM, GY, JE, GX, STHL etc in the UK system

- A place will only have one postcode: counter-example: Büsingen in Germany, which has both a German and a Swiss postcode

@xssfox

fascinating. Here a postcode is a street (if that much). Mind you, it probably covers the same amount of population 😉

@xssfox Aussie postcodes originated from mail truck distribution runs. Some are hilarious, like the Qld PC that’s two areas nearly an hour’s drive apart. Forgotten which town separates them.

@xssfox OK but when was the last time you write code that covered that area? It's a curiosity but with little impact.

@xssfox oh yeah, I recently ran into somebody else's analysis done on a zipcode (US postcode) basis. There are single-point postcodes, single-building postcodes, etc. They change and move wildly
The USPS says: zip codes are mail routes, not polygons, don't try to use them for anything that isn't mail routes, it won't with great. But the US Census publishes shapefiles of zipcodes, but missing the weirdest single point ones and modifying others to be more poly-ish, because people are gonna anyway.

@xssfox easy fix : ban australia

@xssfox ah awesome, another cursed number to add to the library of arcana :D

(that might sound like a complaint but I unironically love shit like this)

@xssfox available for click and collect at your nearest Bunnings: 972km

@xssfox no Australia no, I was already mad at you for your timezones! 😅

@xssfox At least in the case of the US's Zip codes there's also:

- A zip code is associated with only a single location
- A zip code has any geographic region associated with it
- A zip code is associated with something stationary

@xssfox Yeah, writing software that is supposed to run everywhere is difficult.

@xssfox US zip codes can be along roads and intersect. They are tied to mail delivery patterns not area.

@xssfox i know that my postcode has at least two of the same one in the same state, and two states have the same post code

@xssfox Fix Australia 😂

@xssfox
- A postcode will be in a single country

I present 5111 AA, in Baarle-Nassau.

@xssfox US Postal Codes have no real geo point. So building a “find nearest location” using postal codes was only as good as your dataset. Back when I was working on it. The coordinates were tied to the Post Office managing the postal code. So many headaches! And as someone else stated… taxes!

@xssfox Even my much smaller ZIP code in the Philadelphia suburbs, 19010, spans two different counties!

@xssfox In the U.S. where post codes aren’t supposed to cross state lines a few do (89421 McDermitt, Nevada takes a bit of Oregon) and time zones, also while all households in the U.S. are in a post code not all locations are.

@xssfox typical postcode in the Netherlands

@xssfox why are they doing it so wrong?

@xssfox
A shout out to local programmers in the USA: not all postal codes are 5 numerical digits. At least get the format general.

@xssfox Okay, that's amazing. Adding that to my collection of weird trivia. Thanks!

@xssfox and then on the other end of things, Irish post codes contain both numbers and letters and each refers to one exact address.

I grew up in a town with no cities nearby, and was under the impression that each town has one postcode. So I mailed a package to a friend in Sydney by googling Sydney's postcode. The package did not arrive. (It was returned back to me, fortunately.)

@xssfox @sofia
My (Auzy) wife just said its because only 3 people live in that area 🤣

@xssfox Its a special case just hack around it

@xssfox and I thought they were bad in the USA!

@xssfox
I can add another fallacy:
- Everybody has postcodes.
Hong Kong doesn't, which makes the process of paying for things by credit card a bit 'interesting' sometimes where a postcode/zip is required.

@xssfox Here's one:

A postcode is used for delivering mail.

Nope. Not in Ireland. The post office doesn't use it. Addresses have random codes so they can't be hand sorted for mail route delivery.

@xssfox also - small difference in postcode means they're close together. It I guess this is a variation over how they don't map geographically 🤔

@xssfox Another big one is "they are immutable", that one caused me a lot of issues.

@xssfox someone needs to do one of those map size thingies and see what countries fit into that post code.

@xssfox I'm from a fairly rural part of the world, and I'm used to postcodes potentially being very large, but 0872 takes the biscuit.

@xssfox In UK postcode we’re designed around 20;houses and opposite sides of a road had different postodes. The original idea was that letters were sorted into post rounds where the deliverer goes up one side of the road and returns the other side. Last bit never happened

@xssfox To add another point: I live in a country where every street has its own postcode. I've seen international adress forms on websites that consider my postcode to be wrong because someone else entered a different postcode for a different street in the same city.

Some shops want to know your postcode to get a general location (city or region). In my case it leads to a quite more detailed geolocalisation.

@xssfox the whole point of a postcode is lost unless this is logistically the most sensible way of sorting that geographic area's mail, which is odd.

@xssfox As an old mailman, I'm both impressed and horrified…

@xssfox Ireland's eircodes are unique per building. I like this philosophy.

@xssfox @rbanffy That’s like three houses and a shed, some driving between them if they all get post

@xssfox I feel like every "falsehoods programmers believe" list contains multiple counter examples from Australia.

I'm kinda unsurprised when I hear how bad the backbone to the antipodes is from the rest of the world. Makes me wonder if all the programmers rose up and refused to deal with *that* 🤣

@xssfox As someone who has watched hundreds of delivery drivers message me to say they're outside my house when they're actually a block away, I can confirm this is all true.

@xssfox #maps_without_tasmania

@xssfox i used to do logistics analytics and the way my eye is twitching right now at the nightmare that is postal codes. 😱

@sinplicity

@xssfox