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INTERNET-DRAFT
Network Working Group H. Nussbacher
Israeli Inter-University
Computer Center
Y. Bourvine
Hebrew University
June 1993
Hebrew Character Encoding for Internet Messages
This document is an Internet-Draft. Internet-Drafts are
working documents of the Internet Engineering Task Force
(IETF), its Areas, and its Working Groups. Note that other
groups may also distribute working documents as
Internet-Drafts.
Internet-Drafts are draft documents valid for a maximum of six
months. Internet-Drafts may be updated, replaced, or obsoleted
by other documents at any time. It is not appropriate to use
Internet-Drafts as reference material or to cite them other
than as a ``working draft'' or ``work in progress.''
To learn the current status of any Internet-Draft, please check
the 1id-abstracts.txt listing contained in the Internet-Drafts
Shadow Directories on ds.internic.net, nic.nordu.net,
ftp.nisc.sri.com, or munnari.oz.au.
Status of this Memo
This memo provides information for the Internet community. It does
not specify an Internet standard. Distribution of this memo is
unlimited.
Abstract
This document describes the encoding used in electronic mail [RFC822]
for transferring Hebrew. The standard devised makes use of MIME
[RFC1341] and ISO-8859-8.
Description
All Hebrew text when transferred via e-mail must first be translated
into ISO-8859-8, and then encoded using either
Quoted-Printable (preferable) or Base64, as defined in MIME.
Nussbacher & Bourvine Expires December 16, 1993 [Page 1]
INTERNET DRAFT Hebrew email encodings June 1993
The following table provides the four most common Hebrew encodings:
PC IBM PC ISO
Hebrew 8859-8
letter 8-bit 7-bit 8-bit
Ascii EBCDIC Ascii Ascii
---------- ----- ------ ----- ------
aleph 128 41 96 224
bet 129 42 97 225
gimel 130 43 98 226
daled 131 44 99 227
hey 132 45 100 228
vav 133 46 101 229
zayin 134 47 102 230
het 135 48 103 231
tet 136 49 104 232
yud 137 51 105 233
chaf sofit 138 52 106 234
chaf 139 53 107 235
lamed 140 54 108 236
mem sofit 141 55 109 237
mem 142 56 110 238
nun sofit 143 57 111 239
nun 144 58 112 240
samech 145 59 113 241
ayin 146 62 114 242
pey sofit 147 63 115 243
pey 148 64 116 244
zadik sofit 149 65 117 245
zadik 150 66 118 246
kuf 151 67 119 247
raish 152 68 120 248
shin 153 69 121 249
tuff 154 71 122 250
Note: All values are in decimal ASCII except for the EBCDIC column
which is in hexadecimal.
The directionality of the text is visual and not implicit. That
means that the Hebrew text is encoded from left to right (even
though Hebrew text is entered right to left) and is transmitted
from left to right via the standard MIME mechanisms. Future
MIME extensions (to the Content-type) will hopefully contain the
"direction=" option, at which point, it will be assumed that the
default is visual for Hebrew e-mail.
All discussion regarding Hebrew in email, as well as discussions
of Hebrew in other TCP/IP protocols, is discussed in the
ilan-h@vm.tau.ac.il list. To subscribe send mail to
listserv@vm.tau.ac.il with one line of text as follows:
subscribe ilan-h firstname lastname
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INTERNET DRAFT Hebrew email encodings June 1993
MIME Considerations
Mail that is sent that contains Hebrew must contain the following
minimum amount of MIME headers:
MIME-Version: 1.0
Content-type: text/plain; charset=ISO-8859-8
Content-transfer-encoding: BASE64 | Quoted-Printable
Users should keep their text to within 72 columns so as to allow
email quoting via the prefixing of each line with a ">". Users
should also realize that not all MIME implementations handle email
quoting properly, so quoting email that contains Hebrew text may
lead to problems.
In the future, when all email systems implement fully transparent
8-bit email as defined in RFC1425 and RFC1426 this standard will
become partially obsolete. The "Content-type:" field will still
be necessary, as well as directionality (which might be implicit
for 8BIT, but is something for future discussion), but the
"Content-transfer-encoding" will be altered to use 8BIT rather than
Base64 or Quoted-Printable.
Optional
It is recommended, although not required, to support Hebrew encoding
in mail headers as specified in RFC 1342. Specifically, the
Q-encoding format is to be the default method used for encoding
Hebrew in Internet mail headers and not the B-encoding method.
Caveats
Within Israel there are in excess of 40 Listserv lists which will now
start using Hebrew for part of their conversations. Normally,
Listserv will deliver mail from a distribution list with a
"shortened" header, one that does not include the extra MIME headers.
This will cause the MIME encoding to be left intact and the user
agent decoding software will not be able to interpret the mail. Each
user is able to customize how Listserv delivers mail. For lists
that contain Hebrew, users should send mail to Listserv with the
following command:
set listname full
where listname is the name of the list which the user wants full,
unabridged headers to appear. This will update their private
entry and all subsequent mail from that list will be with full
RFC822 headers, including MIME headers.
In addition, Listserv usually maintains automatic archives of
all postings to a list. These archives, contained in the file
"listname LOGyymm", do not contain the MIME headers, so all
encoding information will be lost. This is a limitation of the
Listserv software.
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INTERNET DRAFT Hebrew email encodings June 1993
Example
Below is a short example of Quoted-Printable encoded Hebrew email:
Date: Sun, 06 Jun 93 15:25:35 IDT
From: Hank Nussbacher <HANK@VM.BIU.AC.IL>
Subject: Sample Hebrew mail
To: Hank Nussbacher <Hank@BARILVM>,
Yehavi Bourvine <yehavi@hujivms>
MIME-Version: 1.0
Content-Type: Text/plain; charset=ISO-8859-8
Content-Transfer-Encoding: QUOTED-PRINTABLE
The end of this line contains Hebrew .=EC=E0=F8=F9=E9 =F5=
=F8=E0=EE =ED=E5=EC=F9
Hank Nussbacher =F8=EB=E1=F1=E5=
=F0 =F7=F0=E4
Acknowledgements
Many thanks to Rafi Sadowsky and Nathaniel Borenstein for
all their help.
References
[ISO-8859] Information Processing -- 8-bit Single-Byte Coded
Graphic Character Sets, Part 8: Latin/Hebrew alphabet, ISO 8859-8,
1988.
[RFC822] Crocker, D., "Standard for the Format of ARPA Internet
Text Messages", STD 11, RFC 822, UDEL, August 1982.
[RFC1341] Borenstein N., and N. Freed, "MIME (Multipurpose
Internet Mail Extensions): Mechanisms for Specifying and
Describing the Format of Internet Message Bodies", Bellcore,
Innosoft, June 1992.
[RFC1342] Moore K., "Representation of Non-ASCII Text in Internet
Message Headers", University of Tennessee, June 1992.
[RFC1425] Klensin, J., Freed N., Rose M., Stefferud E., Crocker D.,
"SMTP Service Extensions", February 1993.
[RFC1426] Klensin, J., Freed N., Rose M., Stefferud E., Crocker D.,
"SMTP Service Extension for 8bit-MIME transport", February 1993.
Security Considerations
Security issues are not discussed in this memo.
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Authors' Addresses
Hank Nussbacher
Computer Center
Tel Aviv University
Ramat Aviv
Israel
Fax: +972 3 6409118
Phone: +972 3 6408309
EMail: hank@vm.tau.ac.il
Yehavi Bourvine
Computer Center
Hebrew University
Jerusalem
Israel
Phone: +972 2 585684
Fax: +972 2 527349
EMail: yehavi@vms.huji.ac.il
Nussbacher & Bourvine Expires December 16, 1993 [Page 5]