Subject: RE: Re: BIRD53 - IBIS FILE CHARACTER SET

From: Geoffrey Ellis <[email-masked]>
Date: Mon, 10 Aug 1998 11:06:59 -0700 (PDT)

This should make an interesting discussion at the next IBIS Open Forum.  My
goal is to have a standard which clearly states which characters are allowed
in an IBIS file.  At present, the standard says ASCII, which is a 7-bit code.
Therefore, the wording in this BIRD regarding ASCII is a clarification of
the existing standard, not a change.

Perhaps we should change from ASCII to ISO 8859-1, which supports accented
characters as well (8-bit codes, with the first 128 codes the same as ASCII).
However, this brings up some issues:

  - Will your text editor handle such a file?  Apparently recent versions of
    emacs to have ISO 8859-1 support.  Also vi on SunOS can handle these,
    if the command

        setenv LC_CTYPE iso_8859_1

    is given before editing.  However, use of the LC_CTYPE environment
    variable is not well documented by Sun.  Users in the USA would no doubt
    find many difficulties editing such files.

  - Can 8-bit characters appear in the filenames?  Yes, if the local OS
    accepts such filenames.  Apparently SunOS does.  I am not sure about
    other OS's, in particular MS-DOS.  Note that item 3 of the general syntax
    rules and guidelines says that filenames "must conform to DOS rules".

  - Will you be able to print such a file?  Very few printers in the USA
    directly understand the ISO 8859-1 character set.  For some printers,
    including Postscript printers, it will be possible to print the file using
    a special filter.  Other printers will not be able to print them.

  - Will you be able to E-mail such a file?  Yes, as long as your E-mail
    system accepts attachments of binary files.

Any proposal to change the character set from ASCII to ISO 8859-1 should
address these issues.

***********************************************************************
* Geoffrey Ellis                                                      *
* Cadence Design Systems                    phone:  831-685-6559      *
* 9057 Soquel Drive                         fax:    831-685-6556      *
* Aptos, CA 95003                           E-mail: [email-masked] *
***********************************************************************

>> Only ASCII characters, as defined in ANSI Standard X3.4-1986, may
>> be used in an IBIS file.  ASCII is a 7-bit code; 8-bit characters
>> are not allowed. 
> 
>Is there a technical reason to restrict IBIS to 7-bit codes?
>
>Our in-house IBIS models can contain 8-bit characters - those generated
>by a standard French keyboard - usually in comment fields, or under
>[Source] and [Notes]. I hope that if BIRD53 is accepted, these
>files will pass ibischk, with at worst, the accents being flagged 
>simply for information purposes.