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rfc:rfc1555

Network Working Group H. Nussbacher Request for Comments: 1555 Israeli Inter-University Category: Informational Computer Center

                                                           Y. Bourvine
                                                     Hebrew University
                                                         December 1993
          Hebrew Character Encoding for Internet Messages

Status of this Memo

 This memo provides information for the Internet community.  This memo
 does not specify an Internet standard of any kind.  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
 [RFC1521] 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.
 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
         ---------- -----  ------ -----   ------
         alef        128     41    96     224
         bet         129     42    97     225
         gimel       130     43    98     226
         dalet       131     44    99     227
         he          132     45   100     228
         vav         133     46   101     229
         zayin       134     47   102     230
         het         135     48   103     231
         tet         136     49   104     232
         yod         137     51   105     233
         kaf sofit   138     52   106     234
         kaf         139     53   107     235
         lamed       140     54   108     236

Nussbacher & Bourvine [Page 1] RFC 1555 Hebrew Character Encoding December 1993

         mem sofit   141     55   109     237
         mem         142     56   110     238
         nun sofit   143     57   111     239
         nun         144     58   112     240
         samekh      145     59   113     241
         ayin        146     62   114     242
         pe sofit    147     63   115     243
         pe          148     64   116     244
         tsadi sofit 149     65   117     245
         tsadi       150     66   118     246
         qof         151     67   119     247
         resh        152     68   120     248
         shin        153     69   121     249
         tav         154     71   122     250
 Note: All values are in decimal ASCII except for the EBCDIC column
 which is in hexadecimal.
 ISO 8859-8 8-bit ASCII is also known as IBM Codepage 862.
 The default directionality of the text is visual.  This 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.  Other methods to control
 directionality are supported and are covered in the complementary RFC
 1556, "Handling of Bi-directional Texts in MIME".
 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

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.

Nussbacher & Bourvine [Page 2] RFC 1555 Hebrew Character Encoding December 1993

 In the future, when all email systems implement fully transparent 8-
 bit email as defined in RFC 1425 and RFC 1426 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 1522.  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.

Nussbacher & Bourvine [Page 3] RFC 1555 Hebrew Character Encoding December 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.
 [RFC1425]  Klensin, J., Freed N., Rose M., Stefferud E., and
            D. Crocker, "SMTP Service Extensions", RFC 1425,
            United Nations University, Innosoft International, Inc.,
            Dover Beach Consulting, Inc., Network Management
            Associates, Inc., The Branch Office, February 1993.
 [RFC1426]  Klensin, J., Freed N., Rose M., Stefferud E., and
            D. Crocker, "SMTP Service Extension for 8bit-MIME
            Transport", RFC 1426, United Nations University, Innosoft
            International, Inc., Dover Beach Consulting, Inc., Network
            Management Associates, Inc., The Branch Office, February
            1993.

Nussbacher & Bourvine [Page 4] RFC 1555 Hebrew Character Encoding December 1993

 [RFC1521]  Borenstein N., and N. Freed, "MIME (Multipurpose
            Internet Mail Extensions) Part One: Mechanisms for
            Specifying and Describing the Format of Internet Message
            Bodies", Bellcore, Innosoft, September 1993.
 [RFC1522]  Moore K., "MIME Part Two: Message Header Extensions for
            Non-ASCII Text", University of Tennessee, September 1993.

Security Considerations

 Security issues are not discussed in this memo.

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 [Page 5]

/data/webs/external/dokuwiki/data/pages/rfc/rfc1555.txt · Last modified: 1993/12/22 20:58 by 127.0.0.1

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