This section lists several key Windows 2000 environment variables. Note that environment variables are dereferenced by enclosing the name between percent signs—for example, %SystemRoot%. System and current user environment variables are modified via the path My Computer Properties→Advanced→Environment Variables:
A semicolon-separated list of directories, which are searched in turn for a command entered without a full path.
A semicolon-separated list of file extensions that should be applied in turn to bare command names when searching for the proper executable. Extensions in the list must include the initial period.
The location of the Program Files folder (usually C:\Program Files).
The location of the Windows 2000 system directory (usually C:\WinNT).
Paths to a directory that applications may use for temporary file and scratch storage space.