RE: proposed changes to ACI chapter

I agree with the proposal.  I agree that if you are going to the trouble
of inlcuding the tag you should also put in the attribute.

--
Stuart Galt
SGML Resource Group
stuart.a.galt@boeing.com
(206) 544-3656

 

> -----Original Message-----
> From: Lofton Henderson [mailto:lofton@rockynet.com] 
> Sent: Friday, May 22, 2009 7:53 AM
> To: WebCGM WG
> Subject: proposed changes to ACI chapter
> 
> All--
> 
> Action:
> -----
> Please reply on list to this message:  approve proposed 
> changes; or disapprove and state your reasons.
> 
> What:
> -----
> Following the Wednesday telecon, Dave and a small quality 
> verification task team have looked at Ch.9, the ACI 
> specification and its dtd.  The good news is that it appears 
> to be sound now.  However, the group recommends some simple 
> changes before 2nd LCWD review.
> 
> Details:
> -----
> For seven elements under the (XML) defaultAttributes element, 
> the (XML) attributes associated with the element are optional 
> and a default is given.  Consider for example the lineJoin 
> ACI element [1]:
> 
> [1]
> http://www.w3.org/Graphics/WebCGM/drafts/current-editor-21/Web
CGM21-Config.html#ACI-linejoin
> 
> <!ELEMENT lineJoin EMPTY >
> <!ATTLIST lineJoin
>            lineJoinInd ( 1 | 2 | 3 | 4 ) "1"
>  >
> 
> While this is not incorrect or illegal, strictly speaking, on 
> the other hand it is not sensible when viewed from the 
> perspective of the purpose of the defaultAttributes element.  
> For example, it would allow:
> 
> <lineJoin></lineJoin>
> 
> and that construct would mean that the viewer should use the 
> dtd's default value for lineJoinInd, "1" ('unspecified'),  in 
> rendering.  That value is in fact the CGM:1999 default value 
> for the LINE JOIN element, so the element is essentially an no-op.
> 
> But  the ACI defaultAttributes element was added to webcgm 
> precisely to tie down such underspecified values, and enable 
> uniform viewer results when dealing with the underspecified 
> CGM:1999 defaults.  I.e., if someone is putting a lineJoin 
> element into the ACI file, then the goal presumably is to 
> nail down "unspecified" and tell the viewer to use a 
> particular one of the other 3 well-defined values (which are 
> the legal ways to handle "unspecified").  So the optionality 
> and defaulting of the lineJoinInd attribute does not make 
> sense for this group of elements.
> 
> It makes more sense to require the lineJoinInd attribute 
> whenever the lineJoin element is present.
> 
> Proposal:
> -----
> Change the specification to:
> 
> <!ELEMENT lineJoin EMPTY >
> <!ATTLIST lineJoin
>            lineJoinInd ( 1 | 2 | 3 | 4 ) #REQUIRED  >
> 
> If the ACI has a lineJoin element, it must have a lineJoinInd 
> attribute.
> 
> This proposal would similarly be applied to:  lineCap, 
> edgeCap, lineJoin, edgeJoin, lineTypeCont, edgeTypeCont, 
> restrTextType.
> 
> Additional:
> -----
> Each of these elements also has something like this at the end of it
> definition:  "The default value is '1' or 'unspecified'."
> 
> I would change these occurrences to:
> "Note (informative):  in the CGM:1999 specification, the 
> default value for the associated CGM LINE JOIN Attribute 
> element is "1 (unspecified)."
> 
> It would also be acceptable to simply delete them (speak up 
> if you have a preference here.)
> 
> Tests:
> -----
> No ACI tests are affected.
> 
> Summary:
> -----
> Please reply with:  approval of this proposal; or, 
> disapproval and your reasons.
> 
> Regards,
> -Lofton.
> 
> 
>

Received on Friday, 22 May 2009 14:59:07 UTC