Thanks all. I have successful extend the schema.
Now, I am facing another problem. I want make the first level entries in
my database to be the country list. So, I have configure my slapd.conf to
use a null suffix (suffix "").
When I try using slapadd to add the country list to my database, I
facing the following problem :
Slapadd: database() not configured to hold dn="c=AF" (line=5)
I don't know that's wrong with my slapd.conf . How come I didn't face
the same problem at Openldap 1.2.9 ? Thanks for anyone who can answer my
question !