Deep_Directories

   Both ODS-2 and ODS-5 volume structures support deep nesting of
   directories, subject to the following limits:

   o  There can be up to 255 levels of directories.

   o  The name of each directory can be up to 236 8-bit or 117
      16-bit characters long.

   Complete file specifications longer than 255 bytes are
   abbreviated by RMS when presented to unmodified applications.

   For example, a user can create the following deeply nested
   directory:

   $ CREATE/DIRECTORY [.a.b.c.d.e.f.g.h.i.j.k.l.m]

   A user can create the following directory with a long name on an
   ODS-5 volume:

   $ CREATE/DIRECTORY
   [.AVeryLongDirectoryNameWhichHasNothingToDoWithAnythingInParticular]
 

Additional information available:

Directory_Naming_Syntax