Joined: 08/12/2005 07:39:47
You are referring to the iso code or a national code. We normally use for the adm1 the fips code, or some other code when no fips code is available.
The iso code has some short comings. First it is often defined too late, we need the code when we insert a new admin division. Secondly the iso code is not persistent, it sometimes happens that the codes are shuffled.
We need a code which is available when we need it and it needs to be permanent.
On the lower levels we use national codes where possible.