[DFDL-WG] action 224: add section for implementation defined limits

Thu Oct 24 06:15:17 EDT 2013

Jonathan

We discussed your definitions on the call. I realise that these are lifted 
from XProc, but both Mike and I had to a double take on first reading, 
because the 1st sentence is the same for each. So how about:

[Definition: An implementation-defined feature is one where the 
implementation has discretion in how it is performed, and the 
implementation must document how it is performed.]

[Definition: An implementation-dependent feature is one where the 
implementation has discretion in how it is performed, but the 
implementation is not required to document how the feature is performed.]

 Note that I have re-ordered the definitions as well.

Regards

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

From:   "Cranford, Jonathan W." <jcranford at mitre.org>
To:     Steve Hanson/UK/IBM at IBMGB, 
Cc:     "dfdl-wg at ogf.org" <dfdl-wg at ogf.org>
Date:   19/10/2013 18:59
Subject:        RE: [DFDL-WG] action 224: add section for implementation 
defined limits

All,

Attached are the first few implementation-specific features divided up 
between implementation-defined and implementation-dependent features. 
Three are implementation-defined and two are implementation-dependent.

The intent is to add two definitions to the spec, similar to this snippet 
from the XProc specification (http://www.w3.org/TR/xproc/#conformance):

Conformant processors must implement all of the features described in this 
specification except those that are explicitly identified as optional.

Some aspects of processor behavior are not completely specified; those 
features are either implementation-dependent or implementation-defined.

[Definition: An implementation-dependent feature is one where the 
implementation has discretion in how it is performed. Implementations are 
not required to document or explain how implementation-dependent features 
are performed.]

[Definition: An implementation-defined feature is one where the 
implementation has discretion in how it is performed. Conformant 
implementations must document how implementation-defined features are 
performed.]

I'm still working through the spec; I thought I'd send these off now to 
begin discussion.

Fyi,

Jonathan

>-----Original Message-----
>From: Steve Hanson [mailto:smh at uk.ibm.com]
>Sent: Wednesday, September 18, 2013 3:30 AM
>To: Cranford, Jonathan W.
>Cc: dfdl-wg at ogf.org; dfdl-wg-bounces at ogf.org
>Subject: Re: [DFDL-WG] action 224: add section for implementation defined 
limits
> 
>Jonathan
> 
>Thanks for citing that example. I have added a summary to the minutes of
>yesterday's WG call.
> 
>Please go ahead and trawl the document for implementation 
defined/dependent
>things.
> 
>Please also raise a public comment to track, at
>http://redmine.ogf.org/projects/editor-pubcom/boards/15
><http://redmine.ogf.org/projects/editor-pubcom/boards/15> .
> 
>Regards
> 
>Steve Hanson
>Architect, IBM Data Format Description Language (DFDL)
>Co-Chair, OGF DFDL Working Group <http://www.ogf.org/dfdl/>
>IBM SWG, Hursley, UK
>smh at uk.ibm.com <mailto:smh at uk.ibm.com>
>tel:+44-1962-815848
> 
> 
> 
>From:        "Cranford, Jonathan W." <jcranford at mitre.org>
>To:        "dfdl-wg at ogf.org" <dfdl-wg at ogf.org>,
>Date:        17/09/2013 16:11
>Subject:        [DFDL-WG] action 224: add section for implementation 
defined limits
>Sent by:        dfdl-wg-bounces at ogf.org
> 
>________________________________
> 
> 
> 
> 
>All,
> 
>Action item 224 was raised two weeks ago during the WG call.
> 
>224 Add section for implementation defined limits (All)
>3/9: Several places in the spec cite this, should be grouped. Currently 
partially
>listed in section
>2.6.
>Also note distinction between 'implementation defined' and 
'implementation
>dependent'. Check
>spec for correct usage.
>Resolve during public comment.
> 
>The action item was created based on a comment I made during the call, so 
I
>thought it’d be good to provide an example of the distinction I was 
trying to
>make.
> 
>The W3C XProc specification does a great job of differentiating between
>implementation-defined and implementation-dependent features, with a
>convenient list of each in the appendix.
> 
>Appendix A (http://www.w3.org/TR/xproc/#conformance
><http://www.w3.org/TR/xproc/#conformance> ) contains the following text.
>Conformant processors must implement all of the features described in 
this
>specification except those that are explicitly identified as optional.
>Some aspects of processor behavior are not completely specified; those 
features
>are either implementation-dependent <http://www.w3.org/TR/xproc/#dt-
>implementation-dependent>  or implementation-defined
><http://www.w3.org/TR/xproc/#dt-implementation-defined> .
>[Definition: An implementation-dependent feature is one where the
>implementation has discretion in how it is performed. Implementations are 
not
>required to document or explain how implementation-dependent
><http://www.w3.org/TR/xproc/#dt-implementation-dependent>  features are
>performed.]
>[Definition: An implementation-defined feature is one where the 
implementation
>has discretion in how it is performed. Conformant implementations must
>document how implementation-defined <http://www.w3.org/TR/xproc/#dt-
>implementation-defined>  features are performed.]
> 
>Section A.1 then lists all the implementation-defined features, and 
section A.2
>lists all the implementation-dependent features.
> 
>I think the XProc spec provides a great example to follow on two counts. 
First, it
>formally distinguishes between implementation-defined and implementation-
>dependent features.  The choice of terms isn’t nearly as important as the
>distinction itself, of course:  implementations must document how certain
>features are implemented.  In the DFDL realm, section 2.6 lists some
>implementation limits which always constitute schema definition errors; 
surely
>these are the types of details that must be documented by any DFDL
>implementation.  Using terminology such as “implementation-defined” and
>“implementation-dependent” would flag these types of documentation
>requirements for implementations within the specification.
> 
>Second, all the implementation-defined and implementation-dependent 
features
>are listed in one place in the specification.  I think doing the same in 
the DFDL
>spec would provide a great resource for DFDL implementers.
> 
>Comments?  If everyone agrees, I don’t mind taking the action to search 
through
>the document looking for candidates for inclusion in such a list.
> 
>Sincerely,
> 
>--
>Jonathan W. Cranford
>Senior Information Systems Engineer
>The MITRE Corporation (http://www.mitre.org <http://www.mitre.org/> )
> --
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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
 [attachment "dfdl-implementation-defined.txt" deleted by Steve 
Hanson/UK/IBM] 

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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