RE: [xml-dev] PSVI formalization

[jborden@attbi.com]

Simon,

can we clarify something?

> > Who is talking about adding more complex types than elements and attributes?
> 
...
> ... XML 1.0 types use markup to
> identify structures in content.  For example there may be information of
> type "quantity" that gets marked up as a "quantity" element.  The
> definition of such things is notably called an "element type
> definition".

In talking about "more complex types" there are two different
issues that might get confused.

1) binary datatypes
2) structures composed of elements and attributes

I agree that all this business about different types of
binary datatypes does not have much to do with XML.

But on the other hand, XML types composed of elements and
attributes are perfectly good XML, for example:

(this is written in the XQuery formal semantics language
which is similar to the RELAXNG non-XML syntax)

type person.name.type = 
 element person.name {
    (element family{text} |
     element given{text} |
     element prefix{text} |
     element suffix{text})*
     }

type person.type {
     type person.name+,
     type address*
}

element doctor{
    person.type,
    element license{text},
...
}

element patient{
     person.type,
     element hospital.id{text},
     diagnosis*
}

and there are situations where I might want to select all
"persons" for processing even though they have different
containing elements e.g.

<xsl:template select="person.type">
 ...
</xsl:template>

> 
> From my perspective, you're crossing a line there.  While integers
> aren't particularly harmful in and of themselves, that's the leading
> point of a much much larger wedge.  As that wedge moves deeper (see for
> example, XQuery/XPath) what was once a quantity is now an integer,
> perhaps constrained with min and max values, perhaps given another name
> to identify it as a particular type of integer.

I do agree that an inordinate focus on binary datatypes is
not something that XML ought concern itself with. On the
other hand, I also think that there are excellent reasons
to work with "native XML" types i.e. element and attribute
based structures (a.k.a. "structured datatypes")

I also can't say that I would bet the farm on the "PSVI"
and its details ... it might be a bit more complicated than
it needs to be, on the other hand I haven't spent much
time trying to understand the nitty gritty details of how
it is supposed to work. That is to say, I think "types" in
general are useful, aside from the specific details of how
XSDL and the PSVI are specified. Let's not throw out the
baby with the bathwater. On the other hand, let's be sure
to use clean bathwater :-)

Jonathan