Microsoft’s official Group Policy blog
Administrative templates provide Group Policy setting information for the items that appear under Administrative Templates. Group Policy tools use Administrative template files to populate policy settings in the user interface. This allows administrators to manage registry-based policy settings.Administrative template files in Windows Server 2008 and Windows Vista are divided into ADMX (language-neutral) and ADML (language-specific) files. ADML files are XML-based ADM language files that are stored in a language-specific folder. By default, the %Systemroot%\PolicyDefinitions folder on a local computer stores all ADMX files, and ADML files for all languages that are enabled on the computer.
GP Team (CraigLi)