group and datatypes

[Murata Makoto <mura034@attglobal.net>]

TREX allows content models containing references to datatypes.  I  
think that such content models are sometimes hard to implement.

Consider a pattern as below:

<group><data type="trextutorial:age"/><data type="trextutorial:age"/></group>

where trextutorial:age is the datatype shown in 10.2 of the TREX tutorial.

In my understanding, this pattern matches "16144", since both "16" and "144" 
matches trextutorial:age.  However, there are six possible decompositions 
of "16144" (e.g.,"161" and "44"), and we have to try all of them.

The same thing applies to <oneOrMore>.  For example:

<oneOrMore><data type="dummy:dummy"/></oneOrMore/>, where 

dummy:dummy is a subtype of integer such that permissible values are 
greater than 3 and less than 53.

Consider a string "442".  This is permitted since it can be decomposed into 
"4" and "42".  However, we have to try all possible decompositions.  For example, 
"44":"2" and "4":"4":"2" are such decompositions, and both of them fail.  

Cheers,

Makoto