Re: Namespaces, schemas, Simon's filters.

[Ronald Bourret <rpbourret@rpbourret.com>]

I thought of a shorter summary of this:

1) A fundamental assumption of XML is that element types are global.

2) The namespaces spec reinforces (1) by providing technology that
allows people to make element type names be universally unique.

3) Local element type names are not universally unique. They are only
unique to their containing element type. (In this sense, they are
similar to unqualified attribute names.) This contradicts (1).

4) If a local element type is in a namespace, (2) is no longer true.

5) To provide a workaround for (4), the XML Schemas spec allows local
element type names to be in no namespace at all. This places them
outside the scope of the namespaces spec. (Good practice: If you use
unqualified local element type names, explicitly turn off the default
namespace on the parent element in the instance document. Otherwise,
they could accidentally end up in the default namespace.)

6) Point (5) resolves the technical conflict between local element type
names and the namespaces spec, albeit in a somewhat sneaky manner. It
does not solve the philosophical conflict between local element types
and (1).

-- Ron