Hi RJ,
I asked a similar question about international addresses earlier this year, and got some great answers from Kelli Crispin from the University of North Carolina and Eric Valdesaro from University of Hawaii - thanks Kelli and Eric!
We aren't adding attributes, but we make sure to choose the right country from the drop down. Do look out to make sure the correct country is entered. Every once in a while we get an incoming address with country = United States, and the address is clearly international. And vice versa. If you have several different interfaces that channel data into RE, think about how those channels, or forms, allow users to enter addresses.
Country names are all stored in an RE configuration table. I matched our list of configured countries against the USPS list of countries (https://pe.usps.com/text/imm/immctry.htm) to find countries in the table that need to be corrected, added, consolidated, etc.,. For example, having both "United Kingdom" and "England" listed as countries seemed redundant, and those addresses needed to be grouped when I was compiling stats. By the way, Frank's Compulsive Guide (http://www.columbia.edu/~fdc/postal/) was a good resource when I was trying to understand addressing in the UK.
I decided to give users some address formatting guidelines for 10 "top" countries, determined by how frequently each country occurred in the address table, and where our the majority of our donors and prospects live. The Universal Postal Union is a great resource for understanding address elements in member countries, and I used it a lot to compile my guidelines. My approach is to help users parse international addresses into elements like city, or district, and then map those elements to RE fields. If I'm still having trouble with an address, I find it helpful to try a global address verification tool like the free one on this page:
https://www.melissa.com/address-verification, (Another great tool recommended by Eric) or, enter the address into Google Maps and see what it suggests.
For me, a big challenge to international address standards in RE is RE itself. RE seems to work great for addresses in United States, UK, Australia, New Zealand and Canada. But, according to our IT department, you only have those 5 countries to choose as 'templates' for all other countries. And some fields in the template must read from configuration tables, which also have limitations. Figuring out how to get our other top countries standardized within this limited framework of RE was an area that required some decisions, and some compromises, unfortunately. For example, our configuration table is pre-loaded with US and Canadian States/Provinces. At first I thought we would load Chinese provinces into this table, but some of those are in contradiction with existing states, which is not allowed. HI is the abbreviation for Hainan province in China, and Hawaii. So despite the nominal inconsistency, I decided the province name actually works best in the city, field for China, while leaving the state/province field blank. ...But we need to keep an eye on it because this makes users want to enter the Province name AND abbreviation into the city field. It's also important that anyone sending mail to these international donors understand that the address block generated by RE, is just not going to be correct for some countries. It's a work in progress, and I too would be very interested in hearing how others have solved this problem.
Thanks for posting, and good luck!
Dania Calandrino
Data Integrity Specialist
The Art Institute of Chicago