%boolean; in XML Schema DTD

Hello again,

The DTD for XML Schema defines the entity boolean as:

<!ENTITY % boolean "(true|false)">

However, booleans attributes should accept "0" and "1" as legal values.
Shouldn't the definition be:

<!ENTITY % boolean "(true|false|0|1)">


By the way, the primitive datatype boolean is introduced in Section 
3.2.2 of XML Schema Part 2. However, I cannot find the relation between 
the Lexical representation and the Canonical representation. I guess 
that "1" should be mapped to "true" and "0" to "false", but shouldn't 
this be formally specified ?


Cheers,


   Alain