[x3d-public] Minutes of X3D WG Open Meeting Wednesday 10th May 2017

Tue May 16 20:18:38 PDT 2017

At some point in the discussion of singles & doubles, I ask as to the 
applicability of these discussions to the current V3.x standard or a 
future V4.x standard. It was answered that the discussion was for V3.x.

Leonard Daly

> Attendees:  Roy Walmsley, Leonard Daly, Anita Havele, Vince Marchetti, 
> Don Brutzman, Dick Puk, Michalis Kamburelis,
>
> Apologies received:
>
> =======================================================================================================
>
> Preliminary: *_Welcome, and introductions, as necessary_*
>
> Roy welcomed everyone. No introductions were needed.
>
> =======================================================================================================
>
> Primary discussion topic: *_SFString and MFString in the XML encoding 
> – which quotation marks should be accepted?_*
>
> Ancillary topic: *_MFxxxx fields – use of commas as value separators_*
>
> *__*
>
> ·Introduction: Review of current and reference standards, led by the 
> meeting chair
>
> oISO/IEC 19775-1:2013 clause 5.3.14 SFString and SFString 
> (http://www.web3d.org/documents/specifications/19775-1/V3.3/Part01/fieldsDef.html#SFStringAndMFString)
>
> oISO/IEC 19776-2:2015 clause 5.1.2 Description 
> (http://www.web3d.org/documents/specifications/19776-2/V3.3/Part02/EncodingOfFields.html#Description)
>
> oISO/IEC 19776-2:2015 clause 5.15 SFString and MFString 
> (http://www.web3d.org/documents/specifications/19776-2/V3.3/Part02/EncodingOfFields.html#SFString)
>
> oISO/IEC 19776-2:2015 clause A.4 Fields 
> (http://www.web3d.org/documents/specifications/19776-2/V3.3/Part02/grammar.html#Fields)
>
> oIntroducing JSON (http://www.json.org/)
>
> oISO/IEC 19776-1:2015 clause 5.1.2 Description 
> (http://www.web3d.org/documents/specifications/19776-1/V3.3/Part01/EncodingOfFields.html#5.1.2)
>
> oISO/IEC 19776-1:2016 clause 5.15 SFString and MFString 
> (http://www.web3d.org/documents/specifications/19776-1/V3.3/Part01/EncodingOfFields.html#SFString)
>
> oHTML 5.1 W3C Recommendation, 1 November 2016, clause 8.1.2.3 
> Attributes (https://www.w3.org/TR/html/syntax.html#elements-attributes)
>
> oHTML 5.1 W3C Recommendation, 1 November 2016, clause 9.1 Writing 
> XHTML documents 
> (https://www.w3.org/TR/html/xhtml.html#writing-xhtml-documents)
>
> oExtensible Markup Language (XML) 1.1 W3C Recommendation 4 February 
> 2004, clause 2.3 Common Syntactic Constructs [10] AttValue 
> (https://www.w3.org/TR/2004/REC-xml11-20040204/#NT-AttValue)
>
> Roy opened the discussion with a short review of each of the above 
> references. The reference from ISO/IEC 19775-1 did not have specific 
> impact on the discussions. The next three references from ISO/IEC 
> 19776-2, the Classic VRML encoding, define a string to be have double 
> quotation marks (“), and MFStrings to be an array of strings enclosed 
> in square brackets as array delimiters. Furthermore, an MFString with 
> a single element does not require the square brackets. This principle, 
> of not requiring square brackets for a single value, applies to all 
> MFxxxx fields. The next two references, from ISO/IEC 19776-1, the XML 
> encoding, define a string to have double quotation marks(“) and 
> MFStrings to be an array of strings in single quotes (‘). The 
> remaining three HTML and XML references define attribute values to be 
> enclosed in either double quotes(“) or single quotes(‘).
>
> Don highlighted the existing Mantis issue on this topic that collects 
> some comments. This is issue 1091 - 
> http://www.web3d.org/member-only/mantis/view.php?id=1091 – entitled 
> “Confusion between XML and X3D syntax for SFString”. The related 
> Mantis issues 705 - 
> http://www.web3d.org/member-only/mantis/view.php?id=705 – entitled 
> “Escaping backslashes” and 488 - 
> http://www.web3d.org/member-only/mantis/view.php?id=488 – entitled 
> “Handling of quotation marks” were also noted.
>
> Need to be careful with specifying what we mean by “double quotes” and 
> “single quotes” or “apostrophes”. See 
> https://www.w3.org/TR/REC-xml/#sec-common-syn and 
> https://dev.w3.org/html5/html-author/charref for XML standard. 
> Michalis provided references to clarify this – see 
> http://web3d.org/pipermail/x3d-public_web3d.org/2017-May/006674.html.
>
> The question was also raised about whether the requirement in the XML 
> encoding for an MFString with a single value to be encoded using two 
> sets of quotation marks could be relaxed, in effect dropping the outer 
> set of quotes, just as the Classic VRML encoding drops the array 
> square brackets.
>
> The need for backslash escaping was described. They are needed in the 
> XML encoding because there is both an XML parser and an X3D parser. 
> The question of whether there should be a difference between SFString 
> and MFString escaping requirements was raised. Michalis reported that 
> some implementations do not recognize escape sequences in SFString 
> values – see 
> http://web3d.org/pipermail/x3d-public_web3d.org/2017-May/006690.html.
>
> Michalis noted that the X3D XML encoding is specific about what 
> quotation marks to use, compared to XML. He suggested X3D should 
> permit either sets of quotes, to match the XML / HTML standards. There 
> was general agreement that the specific X3D requirements should be 
> relaxed to match the XML specification for string attributes.
>
> It was agreed that escape sequences are indeed required for MFStrings, 
> but are not be required for SFStrings.
>
> It was proposed that alternative text for clause 5.15 in ISO/IEC 
> 19776-1 should be written. During the discussion, there was a large 
> number of e-mail exchanges on the public list, all stemming from the 
> meeting agenda at 
> http://web3d.org/pipermail/x3d-public_web3d.org/2017-May/006643.html. 
> At the end of the meeting discussions Don and Michalis agreed to put 
> forward new text for consideration.
>
> =======================================================================================================
>
> Close of Meeting: *_Thanks for participating and contributing_*
>
> *__*
>
> Roy thanked everyone for their time to participate and the passionate 
> contributions to the debate.
>
> *__*
>
> Roy Walmsley
>
> X3D WG co-chair
>
>
>
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-- 
*Leonard Daly*
3D Systems & Cloud Consultant
LA ACM SIGGRAPH Chair
President, Daly Realism - /Creating the Future/
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