Re: RELAX NG Tutorial comments

[James Clark <jjc@jclark.com>]

> 1. <optional> versus <zeroOrMore> and <oneOrMore>
> Perhaps "zeroOrOne" could be defined as an alias for "optional"?  The
issue
> is simply one of consistency in naming.

I'm not keen on providing two names for the same pattern.  I think that
confuses users. There are two ways to think of optionality:

- a degenerate kind of repetition

- a choice with the empty sequence

If you think of it the second way (which corresponds to the formal
semantics), then I think there's nothing inconsistent about <optional>.
Although XML Schema treats optionality as degenerate repetition, personally
I find this unnatural.

> 2. use of "href" in <externalRef /> and <include />
> Why not XLinks?  Granted, it's more complex, even for the simple case, but
> also has some interesting potential for external decoration/annotation
with
> linkbases.  Could externalRef and include be defined (alternatively,
> perhaps, rather than as a requirement) to be XLinKs?

RELAX NG already allows you to put xlink:* attributes (indeed any namespace
qualified attribute) on any element.  Requiring xlink:href instead of href
makes things harder to use and I really don't like two names for the same
attribute.

> 3. Qualified names
> The example provided in section 10.2 does not seem terribly useful.  The
> text speaks of multiple namespaces and the need for ease of use, but the
> example uses a single namespace, and the prefixed version is more complex
> than the defaulted version (which is not shown).

I agree that a better example using multiple namespaces is needed.

James