[DFDL-WG] DFDL Action 264- ES in delimiters

Fri Aug 29 03:52:51 EDT 2014

I've re-attached the original discussion around this action to the end of 
this thread, it had got dropped along the way.

The key argument for allowing ES is that "%WSP*;" is the same as the list 
"%ES; %WSP+;" (on parsing, longest match is taken; on unparsing nothing is 
output).

I think Steve's proposal needs one additional restriction - ES as the only 
string literal in the list should be an SDE. In other words, there has to 
be the possibility of an actual terminator.

Regards

Steve Hanson
Architect, IBM DFDL
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh at uk.ibm.com
tel:+44-1962-815848

From:   Mike Beckerle <mbeckerle.dfdl at gmail.com>
To:     "dfdl-wg at ogf.org" <dfdl-wg at ogf.org>, 
Date:   29/08/2014 00:29
Subject:        [DFDL-WG] DFDL Action 264- ES in delimiters
Sent by:        dfdl-wg-bounces at ogf.org

From: Stephen Lawrence
Sent: Wednesday, August 27, 2014 3:20 PM
To: Mike Beckerle
Subject: Re: DFDL Action 264- ES in delimiters

Mike,

The properties that do not allow ES but do allow WSP* (with
restrictions) that I could find are:

- initiator
- terminator
- separator
- textStandardZeroRep

The WSP* restriction for textStandardZeroRep makes sense to not allow
ES. so I think initiator, terminator, and separator are the only
properties where it makes sense to allow ES with the same restrictions
as WSP*. So, here's the Erratum

2.1XX Section 12.2, 14.2. Clarify DFDL Character Class entities allowed
in delimiters

The initiator, terminator, and separator properties can have the ES
character class entity, subject to the same restrictions as WSP*.

Hopefully that's okay and makes sense,
- Steve
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----- Forwarded by Steve Hanson/UK/IBM on 29/08/2014 08:40 -----

From:   Steve Hanson/UK/IBM
To:     "Mike Beckerle" <mbeckerle at tresys.com>, 
Date:   28/08/2014 15:08
Subject:        Fw: [DFDL-WG] ES in delimiters

Reminder to follow-up with Steve Lawrence for next WG call please.

264
Use of ES entity in delimiters (Steve L)
15/7: Proposal to allows ES in delimiters subject to same restrictions as 
WSP* as inconsistent otherwise. Due diligence needed to see whether there 
is anywhere else in the spec that could also allow ES because it also 
allows WSP*.
22/7: With Tresys
29/7: Still with Tresys. Noted that the IBM's comments on the MIL-STD-2045 
additional features document used this feature to negate the need for 
lengthKind 'fixedOrTerminated' (though WSP* would also work).
...
26/8: Still with Steve L

Regards

Steve Hanson
Architect, IBM DFDL
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh at uk.ibm.com
tel:+44-1962-815848
----- Forwarded by Steve Hanson/UK/IBM on 28/08/2014 15:06 -----

From:   Steve Hanson/UK/IBM
To:     Mike Beckerle <mbeckerle.dfdl at gmail.com>, 
Cc:     "dfdl-wg at ogf.org" <dfdl-wg at ogf.org>, dfdl-wg-bounces at ogf.org
Date:   30/06/2014 18:12
Subject:        Re: [DFDL-WG] ES in delimiters

On the face of it, yes it does seem inconsistent. The point being that 
"%WSP*;" is the same as "%ES; %WSP+;" (on parsing, longest match is taken; 
on unparsing nothing is output).

In our NACHA xsds we have:

                        <dfdl:defineFormat name="NACHARecord">
                          <dfdl:format lengthKind="explicit" length="94" 
terminator="%WSP*;"/>
                        </dfdl:defineFormat>

But strictly speaking it should be this because it's an optional new line 
that appears rather than any white space:

                        <dfdl:defineFormat name="NACHARecord">
                          <dfdl:format lengthKind="explicit" length="94" 
terminator="%ES; %NL;"/>
                        </dfdl:defineFormat>

If we allow ES then ES on its own as the only string literal in the list 
should be an error.

Regards

Steve Hanson
Architect, IBM DFDL
Co-Chair, OGF DFDL Working Group
IBM SWG, Hursley, UK
smh at uk.ibm.com
tel:+44-1962-815848

From:   Mike Beckerle <mbeckerle.dfdl at gmail.com>
To:     "dfdl-wg at ogf.org" <dfdl-wg at ogf.org>, 
Date:   26/06/2014 18:17
Subject:        [DFDL-WG] ES in delimiters
Sent by:        dfdl-wg-bounces at ogf.org

Steve Lawrence from the Daffodil project has observed that we're not 
particularly consistent about delimiters and the %ES; entity. 

We allow WSP* with caveat that you can't have initiatedContent, but we 
disallow ES.

There is a use case for optional delimiters e.g.,

initator="%CR;%LF; %ES;" 

meaning absorb and discard an optional CRLF.

Without %ES we end up having to model this syntax as an optional hidden 
element.

Thoughts?

...mikeb

Mike Beckerle | OGF DFDL Workgroup Co-Chair | Tresys Technology | 
www.tresys.com
Please note: Contributions to the DFDL Workgroup's email discussions are 
subject to the OGF Intellectual Property Policy
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Unless stated otherwise above:
IBM United Kingdom Limited - Registered in England and Wales with number 
741598. 
Registered office: PO Box 41, North Harbour, Portsmouth, Hampshire PO6 3AU
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