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From: JPALME@qz.qz.se (Jacob Palme QZ)
Newsgroups: comp.protocols.iso.x400
Subject: Is X.400 good for international mail?
Message-ID: <584410*JPALME@QZ.qz.se>
Date: 6 Jan 91 18:03:55 GMT
References: <1991Jan5.112335.13232@lth.se>
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> From: Dan Oscarsson
> Is X.400 good for international mail?
>
> Some of the things I think is needed:
>
> The body of the mail but be able to contain anything.
>           How is this in X.400?

An X.400 message can consists of several bodies. Each body must
have a body type. The body type for each body is identified by an
object identifier. This means that anyone can define any body
type with his special kind of content.

The X.400 standard contains a number of pre-defined body types.
A user, user group or standards organization who needs some
additional body type can define it, and choose an object identifer
to identify it.

>           Are there some standard formats of the contents?
Yes, there are a number of standardized content formats. The
most important of them are IA5 (=ISO 646), Teletex (=T.61), voice
and fax. New types are being defined, for example will the 1992
version contain special types for "file transmission" based on
the file types defined in FTAM.

>           Is there a standard character set that can take all
>           characters in the world? Like ISO 10646.
I am not sure of ISO 10646 is a standard yet. But when it becomes
a standard, one can expect that there will be defined an X.400
body type for it.

There is an X.400 body type defined by ISO called "general string".
It allows any character set registered by ISO, and assumes that
the string begins with an ISO 2022 escape sequence which defines
which character set is used in the rest of the string. The character
set can, with this body type, also switch in the middle of a
string via additional ISO 2022 escape sequences.

>           Any standard for binary files, inclusion of sound or images?
There is a body type for images in telefacsimile format.

There will be body types for binary files and sound in the 1992
version of X.400. The present version already has a body type
for sound, but does not define which sound encoding to use.

>
> The "headers" must accept any characters in the world.
>           Does X.400 allow anything except ASCII and T.61?
>           Why not an international character set like ISO 10646?

X.400 allows two variants of names in headers (a name can be
given in both variants). One for international use, with a restricted
character set which it is expected that any imaging device anywhere
can render, and any keyboard can produce, and one for national
use within a country.

X.400 uses T.61 for the national character set. ISO 10646 was
not known when X.400 was defined. I can see problems with using
ISO 10646 in headers, since it will only work if all users have
terminals (screens=imaging devices, and keyboards) which can
handle this very wide character set. This will probably not occur
for a long time. With T.61, every country is expected to define
its own subset for national use, which can be handled by the
terminals used within that country.

> The address must be as global as possible without references to a path.
>           That is, I do not want to tell what company is going to
>           deliver my mail! I want just to send it like I do on the Internet,
>           the mail routers (MTA) have do find the way to deliver the mail.

What you are talking about seems to be what in X.400 is called
a "name" and not an "address".

An OR-name in X.400 can consist of two parts. One part called
the directory name, which is the kind of name you like, and one
part called OR-address, which is somewhat more path-oriented.

The concept of domain in internet is more similar to the concept
of "organization" in X.500 and X.400, than to the concept of
domain in X.400.

The Internet mail routers use so-called name-servers to translate
a domain into a path. This means that the same path must be used
for all names with the same domain. In X.400, different pathes
can be used for different names within the same organisation.