When you are deploying a complete, unattended installation of Windows NT Workstation to numerous computers, some of the information you need to supply via answer files (such as the computername) must be unique to each computer. With Windows NT Workstation 4.0, you can use a single answer file for the information that applies to all users, and one or more uniqueness database files (UDFs) to supply information that is specific to a single computer or a small group of computers.
Uniqueness database files (UDFs) are used to provide replacements for sections of the answer file, or supply additional sections. The replacement sections are specified in a text file similar to the answer file. This file is indexed via strings called uniqueness IDs.
The uniqueness database file is used to specify a set of sections that should be merged into the answer file at the start of GUI Setup. This merging takes place before any affected components actually read the internal representation of the answer file. Thus this entire mechanism is totally transparent.
For a discussion of the sections and keys used in answer files and UDFs, see Appendix A, "Answer Files and UDFs."