ISO language codes versus country codes

[Sean M. Burke]

Recently I've been trying my hand at software localization by getting 
friends and friends-of-friends to help me localize the open-source program 
Namp (a.k.a. Apache::MP3 -- <http://namp.sourceforge.net/i18n/burke.shtml>) 
into various languages.  Along the way, I've discovered that many people 
don't know the language tag for their own language, because they (falsely) 
assume it to be the same as the country code.  Consider jp/ja for 
Japan/Japanese, cz/cs, cn/zh, my/ms, si/sl, ua/uk, se/sv, etc.

My question, and it is a historical one, is:
How did these differences come to be?

--
Sean M. Burke    http://www.spinn.net/~sburke/