Microsoft Knowledge Base Article 309689 contains the following summary:
Windows 2000 includes several pre-defined security templates that you can apply to increase the level of security for computers that are running either Windows 2000 Professional or Windows 2000 Server. These security templates are plain text files that you manually edit by using text editor such as Notepad. However, it is recommended that you use the Security Templates Microsoft Management Console (MMC) to make changes to these templates. This article describes how to apply predefined security templates.