Description

   If you try to rename a file that is currently open, the behavior
   is undefined. You cannot rename a file from one physical device
   to another. Both the old and new file specifications must reside
   on the same device.

   If the new_file_spec does not contain a file extension, the
   file extension of old_file_spec is used. To rename a file to
   have no file extension, new_file_spec must contain a period
   (.)  For example, the following renames SYS$DISK:[]FILE.DAT to
   SYS$DISK:[]FILE1.DAT:

   rename("file.dat", "file1");

   However, the following renames SYS$DISK:[]FILE.DAT to
   SYS$DISK:[]FILE1:

   rename("file.dat", "file1.");

                                  NOTE

      Because the rename function does special processing of the
      file extension, the caller must be careful when specifying
      the name of the renamed file in a call to a C Run-Time
      Library function that accepts a file-name argument. For
      example, after the following call to the rename function,
      the new file should be opened as fopen("bar.dat",...):

      rename("foo.dat", "bar");

   The rename function is affected by the setting of the
   DECC$RENAME_NO_INHERIT and DECC$RENAME_ALLOW_DIR feature logicals
   as follows:

   o  DECC$RENAME_NO_INHERIT provides more UNIX compliant behavior
      in rename, and affects whether or not the new name for the
      file inherits anything (like file type) from the old name or
      must be specified completely.

   o  DECC$RENAME_ALLOW_DIR lets you choose between the previous
      OpenVMS behavior of allowing the renaming of a file from one
      directory to another, or the more UNIX compliant behavior of
      not allowing the renaming of a file to a directory.

   Also see the C RTL help for feature logicals DECC$RENAME_NO_
   INHERIT and DECC$RENAME_ALLOW_DIR.