[relax-ng] RELAX NG 2.0 ideas

[James Clark <jjc@jclark.com>]

Here is a list of some ideas I would want to consider for 2.0. Most of these
are things that we considered for 1.0 but decided to leave out.  Issue
numbers are references to

http://www.oasis-open.org/committees/relax-ng/issues-20011011.html

1. Repeat M-N times (issue 11); I think this is particularly useful with
regexes, so if we add regexes along the lines that John C proposes, then I
think the balance tips towards these

2. Richer delimiters for <list> (issue 34); maybe relevant for DSDL
datatypes

3. A way to reference a pattern overriding a particular attribute as XML
Schema allows with xs:restriction (issue 52).

4. Better ways to do references between separate grammars (roughly issue
55); something more like xs:import.

5. Mechanism to constrain mixed content, at least the character repertoire
(issue 41).

6. concur (issue 15)

7. Some way to do exclusions (issue 16)

8. Regexes (along the lines suggested by John C)

9. A way to define/ref name classes

10. A better restriction on <interleave> (issue 40); the current one forbids
some useful things

11. A less free-wheeling approach to annotations

12. Type assignment: a way for the schema to say that it wants
elements/attributes in the instance to be unambiguously associated with
element/attribute patterns in the schema, particularly in conjunction with
11

13. Parameterized patterns (issue 8)

James