Microsoft's ADSI is a set of open interfaces that abstract the capabilities of directory services from different network providers to present a single view for accessing and managing network resources.
Administrators and developers can use ADSI services to enumerate and manage resources in a directory service, no matter which network environment contains the resource. This can be an LDAP-based, NDS-based, or NTDS-based directory. The type of directory service does not matter as long as a service provider is available for that directory service.
Windows NT 4.0 has no true directory services. Windows 2000 has such services. DirectScript allows you to write scripts as if NT 4.0 actually had support for directory services. Your code can then run unchanged under Windows 2000.