[tei-council] <content> vs <mixedContent>

[Sebastian Rahtz]

On 5 Oct 2014, at 23:19, Martin Holmes <mholmes at uvic.ca> wrote:

> discussion? I think the heart of the debate is:
> 
>  - Do we have <mixedContent> alongside <content>, making that the 
> method by which text nodes are allowed within a content model; or
> 
>  - Do we use <content allowText="true"> for the same effect; or

I’d say this one is resolved, as the two models are different, <mixedContent> only
permits a subset of the elements allowed in <content>, so we can’t just create it with
an attribute.

>  - Do we have a sort of object representing a text node, analogous to a 
> reference to an element, which is explicitly positioned within 
> <content>; 

We decided to have <textNode> for this purpose, all happy with that.
except we failed to define what it means. As per your next question:
> 
>  - Do we really know what we mean by a "text node" anyway?

Indeed. The assumption is that it maps to a W3C “string”. But this
a) doesn’t map to the common pattern we use of “text | <g>”, and b)
gives no scope for other data types (e.g. token, number, date etc).
So if we have to provide a way of pointing to other datatypes, it
may well be a bit redundant. Special-casing it as a shortcut implies
its the norm, when I suggest that it isn’t (“text | <gi>” is our norm).
Lou, I think, still believes that it maps to many people’s common-sense
view of a schema, and so should be kept.  

Re <mixedContent>, what’s missing is the definition of what “textual
nodes” are. I feel the same way as about the “text node” in <textNode>, 
that mapping it to “string” implies that this a good norm which is correct for most
cases.  Lou and I see this differently. YMMV.

We can dismiss the fact that I think <mixedContent> is
_per se_ an unnecessary complication, as that's water under the bridge.
Slightly more controversial is the question of whether we’d
actually recast TEI itself in terms of <mixedContent>, or simply
provide it for others.

It’s probably fair to say that these aspects of Pure ODD do
not provide any extra expressivity for the schema designer;
for that we need the contextual constraints, to be discussed.
--
Sebastian Rahtz      
Director (Research) of Academic IT
University of Oxford IT Services
13 Banbury Road, Oxford OX2 6NN. Phone +44 1865 283431

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