Subject: BIRD 26, Syntax guidelines on Tab usage

From: Will Hobbs <[email-masked]>
Date: Fri, 24 Mar 95 12:01:39 PST

Buffer Issue Resolution Document  (BIRD)

BIRD ID#:      26
ISSUE TITLE:   General syntax rules an guidelines on TAB character usage
REQUESTOR:     Arpad Muranyi, Intel Corporation, Folsom, CA

DATE SUBMITTED:                       March 20, 1995
DATE ACCEPTED BY IBIS OPEN FORUM:     Pending

*******************************************************************************
*******************************************************************************

STATEMENT OF THE ISSUE:

Even though TAB characters are allowed in IBIS files and their usage
is legal, there are times when their use can cause problems.  For
example, in conjunction with the 80 character/line limitation, the
golden parser might issue error messages with IBIS files in which the
TAB characters were converted to SPACE characters, but were error free
before the conversion took place.  At such conversions a TAB character
is usually replaced by several SPACE characters.  This can turn a line
originally less than 80 characters into lines more than 80 characters
long.  Conversions like this are usually done by text editors and file
transfering software and may take place unnoticed by the user.

*******************************************************************************

STATEMENT OF THE RESOLVED SPECIFICATIONS:

A new section should be added to the General sytax rules and
guidelines section which recommends that TAB characters should be
avoided if possible.

| General syntax rules and guidelines:                                         |
| .                                                                            |
| .                                                                            |
| .                                                                            |
| 10)  The usage of TAB characters is legal, but they should be avoided as far |
| as possible.  This is to eliminate possible complications which might arise  |
| in situations when TAB characters are automatically converted to multiple    |
| spaces by text editing, file transfering and similar software.  In cases     |
| like that, lines might become longer than 80 characters which is illegal in  |
| IBIS files.                                                                  |

*******************************************************************************

ANALYSIS PATH/DATA THAT LED TO SPECIFICATION:

A user of an IBIS file reported that the Golden parser generated error
messages with IBIS files which he downloaded from the vhdl.org
machine.  These IBIS files were error free when checked with the
Golden parser before and after posting.  The problem was localized to
those lines in the IBIS file in question, which were 76 characters
long and contained a TAB character.  During the user's downloading
process these TABs were converted to eight spaces resulting in 84
character lines which are illegal in IBIS.

*******************************************************************************

ANY OTHER BACKGROUND INFORMATION:

*******************************************************************************