This is a helper variable that defines the registry key under which Windows Explorer folder paths are stored common to all users of the system. It is used by other variables to retrieve shell common folder paths.
You can refer to this variable as <ShellFoldersLM>. Because it is a registry path, it is typically used as <@<ShellFoldersLM>\...additional path...>. Do not change its value; it has been carefully configured for cross-platform compatibility.