various issues

Peter Murray-Rust Peter at
Thu Apr 10 13:16:08 BST 1997

Thanks very much David,
	You have made me feel modestly optimistic - I'll be interested to
hear from Norbert and Tim.  I'll read your pointers asap.

In message <199704101041.GAA00273 at localhost> David Megginson writes:
> Peter Murray-Rust writes:
>  > 	- are AFs part of HyTime or more generally part of SGML?
> Architectural forms were originally specific to HyTime, but in the
> forthcoming Annex 1 of the standard, they have been generalised --
Which?  8879?

> HyTime is one base architecture, but DSSSL is another, as is the
> Canadian GILS project.
>  > 	- does XML support AFs without further revisison?
>  > 	- if not, what has to be added?  or is it possible to build this
>  > 		into tools without breaking the spec?
>  > 	- if tools have to be built, is the processing required at
>  > 		parser level?
> There are different ways of dealing with AFs.  James Clark's SP
> library can do special, smart AF processing, where it actually parses
> the document as if it were an instance of the base architecture rather
> than of the derived architecture, but that is not always necessary (or
> desirable).  XML-based tools can simply look for the <?ArcBase ...?>
> processing instruction and the associated notation declaration, and
> then use the attribute values for processing.  

I'm getting the impression that this is at *processor* level, not parser.
I.e. we might need an AFprocessor tool in our Java toolkit?  Comes between
the parser and the application?

> NXP-based apps, for example, should be able to handle this, but
> DTD-less parsing will not be possible unless the attribute values are
> included in the document instance itself (I consider this a feature
> rather than a bug).

This means they are added to the declaration subset or to the pointers
to the entities?

> The one short-coming is that XML does not support data-attributes, so
> it will not be possible to customise the AF support -- you'll have to
> stick with the defaults.

This sounds reasonable for a first step :-)

>  > 	- do the components belonging to different DTDs have to live in
>  > 		separate files or can they be separated within a single
>  > 		file (e.g. by NOTATIONs)?
> They should be stored in separate files (etc.), just like public
> entity sets.
>  > 	- if someone decides they need AFs are they easy to implement?
>  > 		(for my requirements it looks like an aliasing mechanism
>  > 		would suffice.
> This _is_ an aliasing mechanism, of sorts.

Excellent.  I suspect this is likely to be critical when people start reusing
tagsets.  Other opinions?


Peter Murray-Rust, domestic net connection
Virtual School of Molecular Sciences

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