Subject: RE: Capability terminology

From: "Cancio, Vivian" <[email-masked]>
Date: Fri, 13 Nov 1998 15:19:49 -0800

> > 	[McIntyre, Lloyd]  The DCS does not provide capability
> > information. It sets the session parameters based on the 
> So:  "DIS: This is what I can receive", and "DCS: This is what I'm
> going
> to send".  Right?  
	[McIntyre, Lloyd]  Yes.
> That's an exchange.
> -Dan Wing

My concern are the implications people get from the "capabilities
exchange" terminology, since "capabilities" are not exactly being
"exchanged", even if there is an exchange of "signals" (DIS & DCS)
between the two terminals. The DCS sort of describes the actions that
the sender had taken after having assessed the capabilities of the
recipient. Therefore the recipient has the means to connect and
understand and process the image that it is about to receive.

I had mentioned sometime ago that it would have been nice if we could
send some 'description' of the TIFF attachment being attached (outside
of the TIFF file - don't know where) -  matching the model of the DCS -
so that receiving SMTP IFax servers could determine a mismatch to the
capabilities of the recipient's and could send back a NAK DSN
immediately, without the message ever being opened or processed. I was
told this was not that simple, so I didn't insist, but if we could do
that, it will be close to how you use a DCS.

Interestingly enough that DIS stands for "Digital Identification Signal"
Vivian

P.S. Paul Smeulders description seems very comprehensive 

FYI.

DCS stands for "Digital Command Signal"

---

From: Dan Wing <[email-masked]>
Date: Fri, 13 Nov 1998 15:25:04 -0800 (PST)

> that, it will be close to how you use a DCS.

Neat idea on the surface, but what should a receiver do when the external
file format description doesn't match the internal (TIFF) description?

I know we could specify that in a standard, but because the information
is already in the self-describing TIFF file, it seems unnecessarily
redundant and prone to error:

As a simple example:

  2 + 2 = 5

Is the sum really "4" or is there a missing "+1" on the left (or "-1"
on the right?

-Dan Wing

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From: Al Gilman <[email-masked]>
Date: Fri, 13 Nov 1998 18:57:17 -0500 (EST)

Only programmers could be engaging in this debate. 

I looked in my _Webster's New Collegiate Dictionary_ which
is hardly new. [c 1975]

The dominant meaning for exchange involves transactions where
what is given and what is received are not of the same category,
but are, for reasons known only to the exchanging parties,
regarded as leaving neither party to the paired transfers as
injured.

So exchanging information about print capabilities for TIFF
formatted data appropriate to that capability is an exchange
of capability knowledge in the dominant plain English sense
of the word, if I read the dictionary right.

It should not be necessary to swap capability for capability for
it to be recognize as an exchange of capability.  At least, not
in English.

The stock exchange does not primarily deal in swaps.

Al