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From: ted@imsvax.UUCP (Ted Holden)
Newsgroups: net.micro.pc
Subject: More on WordPerfect and the DIF standard
Message-ID: <491@imsvax.UUCP>
Date: Sat, 4-Jan-86 14:13:25 EST
Article-I.D.: imsvax.491
Posted: Sat Jan  4 14:13:25 1986
Date-Received: Mon, 6-Jan-86 03:14:59 EST
Organization: IMS Inc, Rockville MD
Lines: 74


     In a reply to my article concerning WordPerfect and the Navy DIF standard,
H. Silbiger of Bell Labs gives a (reasonably) accurate account of the
circumstances involved in the development of the DIF, but also provides
several pieces of mis-information which I would like to clear up.

>The first thing they agreed on that only functions everyone
>used would be supported.

     This should read "would be supported IN FILE STRUCTURE".  This
doesn't mean that you LOSE things such as right-flush tabs, footnotes,
or the WordPerfect paragraph numbers which fall outside of the 45
functions retained by DIF;  it simply means that a reasonable
WordPerfect to DIF conversion routine would transmit these things on a
PAGE-IMAGE basis only, e.g. translate a right-flush tab into the
appropriate number of blank spaces etc.  Conversely, it makes no sense
for other standards, such as the ISO,to include paragraph numbers as a
file structure item, when most word processors or even a reasonable
number of word processors don't have them.

>Next they looked at those functions
>for which evryone used the same control code.  Those were accepted.
>Next they all agreed on a code for all other functions for which
>there was no common code.

     This is simply wrong.  No two vendors used the same code for
ANYTHING, there being as many file structures for word processors as
there are people WRITING word processors.  DIF codes, other then the 13
older VT100 type codes for things such as bolding and justifying which
the standards committees forced on us, consist of an escape followed by
a left bracket, then a numeric parameter of some sort, then a dollar
sign indicating the end of the parameter, and lastly a character
indicating the nature of the code.  A left Margin setting of 11 would be

     Escape[11$@

the "@" symbol being the code for left margins.  Of the 128 Ascii codes
available, we have used 33; so much for the notion that the DIF is not
extensible for future needs.

>The DIF work should thus be seen as a stop-gap measure to
>achieve some limited degree of interchange. It is not
>easily extensible, and cannot support compound documents.

     The DIF is here and available NOW;  the standards Mr. Silberman
speaks of exist on paper and are likely to remain so, and there are
several good reasons for believing that the Navy DIF standard will be
the best system of document conversion available in the real world for
some time to come.

     Actually writing DIF conversion routines which performed acceptably
turned out to be FAR more difficult than anticipated, taking six months
to a year in most cases.  There have been several outright failures by
major corporations attempting to write acceptable DIF routines, and the
ones which do work and which the Navy has validated are typically on
revision 150 or 200 at the time of acceptance.  People who have actually
been through this process are not likely to want to hear about any
standard much more complicated than DIF.

     All attempts to write DIF conversion routines as if they were
simply one-to-one table look-up type programs failed miserably and were
unacceptable to the Navy, as I will shortly document and explain in one
or two future articles.  As I have stated previously, SSI's attempt at
including Navy DIF in their little Convert routine falls into this
category and basically doesn't work at all.  I.M.S. has a set of real
DIF filters for WordPerfect which we wrote as a means of bidding federal
contracts with PCs.  Anyone wanting a copy of these should send a
purchase order and a check for $100 to:

     Integrated MicroComputer Systems
     DIF Development Group
     6110 Executive Blvd.,
     Rockville, Md. 20852
     Suite 750