various issues

Peter Murray-Rust Peter at
Thu Apr 10 09:56:16 BST 1997

	This sounds exactly what is needed but the bad news is that
I know nothing about architectural forms.  I suspect this is true for
some other readers of this list as well.  I would be grateful for any pointers
(and brief explanations here if possible.)  Here are some very naive

	- are AFs part of HyTime or more generally part of SGML?
	- 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?
	- 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)?
	- if someone decides they need AFs are they easy to implement?
		(for my requirements it looks like an aliasing mechanism
		would suffice.
In message <199704100019.UAA00272 at localhost> David Megginson writes:

> Peter Murray-Rust writes:
>  > The major problem is namespace collisions between ElementTypes.
>  > Does anyone have a solution?  What if the incompatible document is
>  > in a separate valid document (i.e. with DOCTYPE).  I'd value
>  > ideas/epxerience here, otherwise we will have to produce some
>  > kludge.
> The solution is to define tables (etc.) as base architectures, and
> then to map specific DTDs using architectural forms, something like
> this:
>   <?ArcBase xmlTable>
>   [notation and entity declarations omitted]
>   <!ELEMENT table     (tr+)>
>   <!ATTLIST table
>     xmlTable #FIXED "xmlTable">
>   <!ELEMENT tr        (tc+)>
>   <!ATTLIST tr
>     xmlTable #FIXED "xmlTableRow">
>   <!ELEMENT tc        (#PCDATA)>
>   <!ATTLIST tc
>     xmlTable #FIXED "xmlTableCell">
> Presto -- no element-type-name collisions!

I'm assuming that you are taking HTML3.2 as an example (I'm happy with
that :-).  If so, which document does the above occur in?  I can see that
it might alias a 'foreign' DTD's TABLE to xmlTable but what if there is
another DTD with TABLE in.  Or does the ArcBase PI imply a scope for the
declarations which only exists in a small region.  (If so this is clearly
something the parser has to resolve).

If I'm on the right track, what do the parser authors think about 
implementing AFs?  Is it a lot of work?


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

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