Enabling DECC$RENAME_ALLOW_DIR restores the prior OpenVMS
    behavior of the rename function by allowing conversion to a
    directory specification when the second argument is an ambiguous
    file specification passed as a logical name. The ambiguity is
    whether the logical name is a UNIX or OpenVMS file specification.
    Consider the following example with DECC$RENAME_ALLOW_DIR
    enabled:

    rename("file.ext", "logical_name")
                            /*where logical_name = dev:[dir.subdir]*/
                            /* and :[dir.subdir] exists.          */

    This results in:

    dev:[dir.subdir]file.ext

    This example renames a file from one directory into another
    directory, which is the same behavior as in legacy versions
    of OpenVMS (versions before 7.3-1). Also in this example, if
    dev:[dir.subdir] does not exist, rename returns an error.

    Disabling DECC$RENAME_ALLOW_DIR provides a more UNIX compliant
    conversion of the "logical_name" argument of rename. Consider the
    following example with DECC$RENAME_ALLOW_DIR disabled:

    rename("file.ext", "logical_name")
                        /* where logical_name = dev:[dir.subdir] */

    This results in:

    dev:[dir]subdir.ext

    This example renames the file using the subdir part of the
    "logical_name" argument as the new filename because on UNIX
    systems, renaming a file to a directory is not allowed. So
    rename internally converts the "logical_name" to a filename, and
    dev:[dir]subdir is the most reasonable conversion it can perform.

    This new feature switch has a side effect of causing rename to a
    directory to take precedence over rename to a file. Consider this
    example:

    rename ( "file1.ext", "dir2" )      /* dir2 is not a logical */

    With DECC$RENAME_ALLOW_DIR disabled, this example results in
    dir2.ext, regardless of whether or not subdirectory [.dir2]
    exists.

    With DECC$RENAME_ALLOW_DIR enabled, this example results in
    dir2.ext only if subdirectory [.dir2] does not exist. If
    subdirectory [.dir2] does exist, the result is [.dir2]file1.ext.

                                   NOTE

       If DECC$RENAME_NO_INHERIT is enabled, UNIX compliant
       behavior is expected, so DECC$RENAME_ALLOW_DIR is ignored,
       and renaming a file to a directory is not allowed.