Countries visited

We travelled in November to Korea and Japan with our friends Paul and Cathy... which means we can add 2 countries to our list of visited countries. We often talk about tracking which countries we've visited. My list of countries is, by order of Cecilia's list:

Canada, Mexico, USA, Austria, Belgium, Czech Republic, Czechoslovakia, France, Germany, East Germany, Greece, Holland, Hungary, Italy, Portugal, Spain, Switzerland, United Kingdom, Morocco, Japan, South Korea.

A total of 21 countries. Clearly some more work in Asia, South America and Africa is in order.

And as always, the issue of "what is a country" comes up.. Some of the neat boundary conditions:
- Overnight stays only?
- Have to remember the visit? excludes visits when young and/or inebriated?
- If the place visited is part of a country that splits? Is Prague visited when part of czeckoslovakia and also when part of czech replublic count as 1 or 2 countries?
- part of a country that merges? Does East Berlin visited on October 2 and 3rd 1990 count as 2 countries or one?
- How about protectorates? Guam, etc.?
- The one country/two country debates like Taiwan compared to China. Does visits to Taiwan and mainland China count as 2 or 1?

My rough criteria: If a country changes is "state", that is splits/joins with other areas, each visit counts. For example, in 1990 I visited Prague - when in czechoslovakia - and East Germany when it was a separate country. I also visited Prague in 1999 as part of Czech replublic (what a party when the Czechs beat Russia for Olympic Gold in hockey) and I visited Germany in 1994. I count these as 4 countries as it seems to me that these are quite distinctly different political entities. I don't count Scotland/Wales/Ireland as separate entities.

There's some organizations that face this problem already, notably the UN and the Olympics. I think I roughly use the UN criteria. I don't use the Olympic criteria in at least one regard because I don't count Scotland/...