SDD Specifications Document

Leigh Dodds ldodds at INGENTA.COM
Thu Feb 24 09:40:43 CET 2000


Just to respond to the following mentioned by Bob:

> (b). Mixed content (a mixture of text and elements) is a really
> bad idea, as is well known in the SGML community. Our own
> limited experience has been that dealing with it in display code
> necessitates to code obscurely. I can't tell whether anything
> in the proposal would lead this way. Maybe some pseudo-code
> XML-like examples would enlighten.

Mixed content can certainly be difficult to manage, although
people are using it on a daily basis when they write HTML,
so it can't all be bad!

Seriously though, I had been thinking that the 'notes'
and other free text sections in the format would use XHTML
derived tags to describe its presentation. Perhaps its
worth exploring this further.

Firstly, for non-markup people. Mixed content is markup
which contains free text interspersed with additional tags.

e.g. <notes>This is <b>mixed</b> content</notes>

An (trivial) example using XDELTA syntax:

<character number="2">
   <description>main colour of inner part of front wing</description>
   <image num="2" mime="image/jpeg" href="lepc02.jpg" />
   <multi type="unordered">
        ...states removed...
   <notes>I should stress here that there <em>may be</em>
other wings colours yet to be determined</notes>

Where <em> denotes emphasised text.

This facilitates the production of a nicely formatted display,
at least for HTML.

An alternative which removes mixed content (I'll just
reproduce the notes tag for clarity:

<text>I should stress here that there </text>
<em>may be</em>
<text>other wings colours yet to be determined</text>

I believe this is less readable, and involves more markup effort
from the user.

Of course I might be barking up the wrong tree, and this
kind of markup isn't a requirement.

The issue is related to how the textual content in the data
is to be presented to the user, and isn't something we've
explored yet.

The main problem with mixed content is it makes life difficult
for parser and tool writers. It does make some things easier
for the user, like readability.



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