     If you think of the "directory hierarchy" as an inverted tree containing
all directories on Multics, then there must be a root directory from which
all the others stem.  The root directory on Multics doesn't have a name.  When
a line of "directories" going back to the root is displayed, the root is
indicated by a greater-than character (>) at the left.  For example, when you
use the print_wdir command, it prints your working directory and the path back
to the root:

>user_dir_dir>Mktg>Jones

     The directory immediately following the root, named user_dir_dir, is a
system directory.  It contains all of the project directories.   It is one of
the six system directories on Multics.  All of the system directories are
contained in the root; they are the only directories contained in the root.
