NFS-to-OpenVMS Filename Mapping

This appendix is a supplement to the NFS-OpenVMS Client and NFS-OpenVMS Server chapters in this guide.

The following filename mapping rules are necessary because:

• TCPware Client must map (translate) special characters in NFS server filenames that are not valid in OpenVMS filenames.
• TCPware Server must map special characters in filenames users create on the NFS system client host that are not valid in OpenVMS filenames.

OpenVMS disk filenames can be 39 characters long (as can file extensions) and include only the following characters:

0 through 9, A through Z, a through z, dollar sign ($), hyphen (-), and underscore (_)

OpenVMS files also include version numbers (after the semicolon) that cannot exceed the value 32767. The Server preserves these version numbers, and hard-links the highest numbered version to an unversioned filename (see the Note at the bottom of Table A-2).

NFS filenames can have any of the ASCII characters except the null character (octal 000) and the slash (/, or octal 057), which delimits directory levels. BSD UNIX filenames can have up to 255 characters.

The Client and the Server use the same filename mapping schemes. Three types of mapping schemes are available:

• SRI International mapping, the default scheme between UNIX and OpenVMS systems

Table A-1 shows the default SRI International mapping.

• PATHWORKS non-case-sensitive mapping (NFS-OpenVMS Server only)
• PATHWORKS case-sensitive mapping (NFS-OpenVMS Server only)

Table A-1 NFS-to-OpenVMS Character Sequence Mapping

ASCII character...	Is mapped in OpenVMS to...	With octal value...
Ctrl/A (soh)	$4A	001
Ctrl/B (stx)	$4B	002
Ctrl/C (etx)	$4C	003
Ctrl/D (eot)	$4D	004
Ctrl/E (enq)	$4E	005
Ctrl/F (ack)	$4F	006
Ctrl/G (bel)	$4G	007
Ctrl/H (bs)	$4H	010
Ctrl/I (ht)	$4I	011
Ctrl/J (nl)	$4J	012
Ctrl/K (vt)	$4K	013
Ctrl/L (np)	$4L	014
Ctrl/M (cr)	$4M	015
Ctrl/N (so)	$4N	016
Ctrl/O (si)	$4O	017
Ctrl/P (dle)	$4P	020
Ctrl/Q (dc1)	$4Q	021
Ctrl/R (dc2)	$4R	022
Ctrl/S (dc3)	$4S	023
Ctrl/T (dc4)	$4T	024
Ctrl/U (nak)	$4U	025
Ctrl/V (syn)	$4V	026
Ctrl/W (etb)	$4W	027
Ctrl/X (can)	$4X	030
ASCII character...	Is mapped in OpenVMS to...	With octal value...
Ctrl/Y (em)	$4Y	031
Ctrl/Z (sub)	$4Z	032
Ctrl/[ (esc)	$6B	033
Ctrl/(fs)	$6C	034
Ctrl/] (gs)	$6D	035
Ctrl/^ (rs)	$6E	036
Ctrl/_ (us)	$6F	037
SPACE (sp)	$7A	040
!	$5A	041
"	$5B	042
#	$5C	043
$	$$ (See Rule 9 in Table A-2)	044
%	$5E	045
&	$5F	046
'	$5G	047
(	$5H	050
)	$5I	051
*	$5J	052
+	$5K	053
,	$5L	054
-	same	055
.	. or $5N (See Table A-2)	056
/	not mapped (directory delimiter)	057
0 to 9	same	060 to 071
:	$5Z	072
ASCII character...	Is mapped in OpenVMS to...	With octal value...
;	$7B	073
<	$7C	074
=	$7D	075
>	$7E	076
?	$7F	077
@	$8A	100
A to Z	same	101 to 132
[	$8B	133
	$8C	134
]	$8D	135
^	$8E	136
_	same	137
`	$9A	140
a to z	same	141 to 172
{	$9B	173
|	$9C	174
}	$9D	175
~	$9E	176
DEL	$9F	177
octal 200 to ¿	$200 to $277	200 to 277 (Multinational)
À to octal 377	$300 to $377	300 to 377 (Multinational)

The NFS-to-OpenVMS filename translation rules in Table A-2 are based on the character mapping scheme in Table A-1. The OpenVMS-to-NFS mapping rules are the converse of these rules.

Table A-2 NFS-to-OpenVMS Filename Translation Rules

Rule	What happens to filenames from NFS to OpenVMS...
1	Lowercase characters become uppercase (unless Rule 2 applies; see also Rule 3): foobar.txt becomes FOOBAR.TXT;1
2	Initial uppercase characters or a sequence of case-shifted characters get a $ prefix: CaseShiftedFile becomes $C$ASE$S$HIFTED$F$ILE.;1
3	An unversioned file gets a version number preceded by a semicolon: foobar.txt becomes FOOBAR.TXT;1
4	If a filename does not include a file extension dot (.), it gets one before the version number semicolon: foobar becomes FOOBAR.;1
5	After being translated, if a filename (or its extension after the dot) has more than 39 characters or the version number (after the semicolon) is greater than 32767, the file will not show up in an OpenVMS listing.
6	The first dot in a filename is preserved, unless the result fails the 39-character extension limit test in Rule 5 (if so, the dot becomes $5N). Each successive dot becomes $5N, unless the filename exceeds the limits in Rule 5. more.file.txt becomes MORE.FILE$5NTXT;1
7	If the filename is a directory name, each dot in it becomes $5N and the filename gets the .DIR extension: dot.directory.list becomes DOT$5NDIRECTORY$5NLIST.DIR;1
8	Invalid OpenVMS characters become the escape character sequences in the second column of Table A-1 ($ followed by a digit and a letter): special#character&file becomes SPECIAL$5CCHAR$5FFILE.;1 (# becomes $5C and & becomes $5F)
9	Any existing $ becomes $$ (plus any $ added due to Rule 2 or 8 above): dollar$Sign$5cfile becomes DOLLAR$$$S$IGN$$5CFILE.;1

Note! Many UNIX applications use only unversioned filenames and simply overwrite existing files. Normally, if you create a file with a new version number in OpenVMS, the Client and Server include the version number when displayed on the NFS server. Also, if foobar;9 is the highest-numbered version in NFS, the Client creates an unversioned foobar file and hard-links to it. You can limit this versioning by specifying the /NOVERSION qualifier with the Client NFSMOUNT command; this limits the number of versions created to one, unless an accompanying Attributes Data File (ADF) specifies otherwise.

Keep in mind that the highest numbered version is not necessarily the most recent one, such as when you create a file explicitly with a lower version number than an existing one. For example, the Client and Server normally do not append a version number at the end of a foobar;1 file and just keep it as foobar, unless you explicitly specify foobar;1 with an already existing higher version of the file.