Proposal for restructuring 7.1

The BNF in 7.1 is very difficult to understand.  However, to really understand 
the syntax of RELAX NG, people have to read this BNF.  Simplification of this 
BNF help readers significantly.

This BNF sometimes repeats what is already said in the other part of the spec 
and sometimes introduces new restrictions.   I think that we should introduce 
new restrictions one at a time.

Therefore, I propose to restructure 7.1 as follows.

1) Make an informative appendiex and move this entire BNF to this appendiex .

2) Define "dataValueChoice", "dataValue in new 7.1 by 
   by using relevant production rules.

3) Introduce restrictions on <except> in new 7.2.

4) Introduce restrictions on <key> and <keyRef> in new 7.3

5) Introduce restrictions on <list> in new 7.4.  This requires 
   introduction of "token" and "tokens".

6) Introduce restrictions on <attribute> in new 7.5.  This requires 
   introduction of "value".

7) Introduce restrictions on name classes in 7.6.  We can simply 
   repeat relevent rules currently placed in 7.1.

8) Introduce restrictions on <oneOrMore> and <attribute> in 7.7.

Cheers,

Makoto