base file system	- Another name for root file system.

base root		- The name of the root directory of the root file
			  system.

mount point		- The location at which the (virtual) overlay file
			  system is accessible to the user.  Note that at
			  current this can NOT be the base file system, but
			  this may change in the future.

original root		- Another name for base root.

overlay file system	- The name of the (real) filesystem which stores
			  updates to the root file system (for the virtual file
			  system) so that the root file system is not actually
			  affected by any updates.

overlay root		- The name of the root directory of the overlay file
			  system.

root file system	- The name of the filesystem being overlayed; this is
			  the "original" or "base" filesystem from which files
			  are retrieved.
