Re: [Cellar] [Tools-discuss] expressing both svg graphics and ascii-art fallback within an rfc2xml version 3 file?

[Henrik Levkowetz <[e-mail]>]

Hi David,

Response at the bottom:

On 2019-09-01 18:29, Michael Richardson wrote:
> 
> {reposting to tools-discuss}
> 
> Hello cellar,
> 
> The draft of FFV1 now uses xml2rfc version 3 as defined at
> https://tools.ietf.org/html/rfc7991
> <https://tools.ietf.org/html/rfc7991>. Presently in the markdown source of
> the FFV1 draft, the math is maintained in both LaTeX expressions (which are
> converted to SVG for inclusion in the RFC XML) as well as an Ascii Art
> representation (heavily reliant on functions defined within the draft). For
> example: 
> 
> vs
> 
> r_{i} = floor( ( R_{i} * S_{i,C_{i}} ) / 2^8 )
> 
> Whether in SVG or ascii art, this data is contained by the <artwork> node in
> rfc2xml version 3. In https://tools.ietf.org/html/rfc7991#section-2.5
> <https://tools.ietf.org/html/rfc7991#section-2.5> it states, 
> 
>    Alternatively, the "src" attribute allows referencing an external
>    graphics file, such as a vector drawing in SVG or a bitmap graphic
>    file, using a URI.  In this case, the textual content acts as a
>    fallback for output representations that do not support graphics;
>    thus, it ought to contain either (1) a "line art" variant of the
>    graphics or (2) prose that describes the included image in sufficient
>    detail.
> 
> A bit later it says that SVG data may be encoded and stored within the
> <artwork>’s @src attribute such as  
> 
>    o  As a data: URI, such as: <artwork type="svg" src="data:image/
>       svg+xml,%3Csvg%20xmlns%3D%22http%3A%2F%2Fwww.w3…">
> 
> So from this I was hoping we could work on one draft rfc2xml version 3 file
> that could use the SVG image data or use the ascii art as a fallback; however
> when I try to craft the <artwork> node with both such as: 
> 
>    <artwork type="svg" src="data:image/svg+xml,ENCODED_SVG_MATH_IMAGE_HERE”>FALLBACK_ASCII_ART_HERE</artwork>
> 
> then the output “v3-plaintext” output of the conversion tool at
> https://xml2rfc.tools.ietf.org/experimental.html
> <https://xml2rfc.tools.ietf.org/experimental.html>, does not use the textual
> content of the <artwork> node as a fallback but instead places a warning such
> as 
> 
>    (Artwork only available as svg: No external link available, see
>    draft-ietf-cellar-ffv1-08.html for artwork.)
> 
> Is it feasible (recommended?) to have one rfc2xml XML document that could be
> a source for both plaintext formats (using an ascii art fallback) and
> non-plaintext formats such as HTML and PDF which would use the embedded SVG
> data?

Yes.  The specification of how to handle the text fallback in the RFC 799x
documents was in part contradictory, and also not as extensible and easily
editable as one could wish.  It currently looks like rfc7991bis largely will
follow the proposal discussed on the xml2rfc-dev list earlier this year, and
captured in the xml2rfc implementation notes draft here:

https://tools.ietf.org/html/draft-levkowetz-xml2rfc-v3-implementation-notes-09#section-3.1.1

which introduces an <artset> element which can contain multiple <artwork>
elements with different type attributes, for instance (artwork and some
details omitted:

  <artset>
    <artwork type="svg" src="..."/>
    <artwork type="ascii-art" ...>
	# ascii art
    </artwork>
  </artset>

For more on this, and for a light introduction to the v3 schema, check:
http://tools.ietf.org/src/xml2rfc/trunk/cli/doc/xml2rfc3.html#artwork-alternatives


Best regards,

	Henrik


> 
> Kind Regards,
> Dave Rice
> 
> 
> 
> 
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