Search notes:

%CommonProgramFiles%

The default location of %CommonProgramFiles% seems to be C:\Program Files\Common Files
Some subdirectories might be:

See also

CommonFilesDir and CommonW6432Dir under the registry key HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion
%CommonProgramFiles(x86)%
The .NET enumeration System.Environment+SpecialFolder.
The parent directory C:\Program Files

Index