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From: mark@cbmark.cbcc.att.COM (Mark Horton)
Newsgroups: comp.protocols.iso.x400
Subject: Re:  Printable format (was: Re:  ISO/CCITT meeting report, Munich July 1990)
Message-ID: <9008101534.AA00934@cbmark.cbcc.att.com>
Date: 10 Aug 90 17:51:06 GMT
Lines: 28
Approved: usenet@ICS.UCI.EDU
Autoforwarded: true

>As a member of RARE WG1, which is more or less responsible for putting the
>format forward, I think I can state that the reason ; was chosen for a
>delimiter
>and not / was that / is a PrintableString character, while ; is not.
>This means that in order to use /, we have to define a quoting syntax, while
>using ; quotes would not be needed.
>
>Of course we will have to rework that in order to write down 88 version
>T.61 addresses....

Not to mention UNIX systems.  Since ; is special to the UNIX shell,
addresses with ; in them simply can't work on UNIX systems.  (You
can quote things to one level of shell, but the quotes will be stripped
off and the next time a shell sees it, such as on a remote machine or
in an internal mail switch handing off to an X.400 gateway) the semicolon
will split the line into two separate shell commands.

If you're willing to have a syntax that can't be used on UNIX systems,
the semicolon syntax is very attractive.  However, in the real world
UNIX systems account for a very significant fraction of existing networks
and email systems, and a standard they cannot implement will probably
wind up being ignored or replaced with one that can be used.

Quoting mechanisms are unavoidable in the real world.  / may be a
printable character, but it will be a rare one, so there won't be
much inconvenience imposed by making it be quoted.

	Mark