Why driver does not need to be registered?

Hi

I'm using postgresql-8.3-604.jdbc3.jar driver

I have a very simple java program to inspect what drivers are initially loaded:

import java.sql.DriverManager;

public class TestDrivers {
   
    public static void main(String [] argv) {
       
    
        java.util.Enumeration myDrivers = DriverManager.getDrivers();

    while (misDrivers.hasMoreElements()){
       System.out.println(misDrivers.nextElement());
    }
       

   
    }
   
}