Q about DTD for XML Schema

[Henry, this is mostly a question for you.]

The XML Schema datatype spec says [1]:

<quote>
3.2.2 boolean

[Definition:]  boolean has the *value space* required to support the
mathematical concept of binary-valued logic: {true, false}. 

3.2.2.1 Lexical representation

An instance of a datatype that is defined as *boolean* can have the
following legal literals {true, false, 1, 0}. 
</quote>

So I gather the allowable values in a document instance
for something of type boolean are one of the four strings
true, false, 1, 0.  Correct?

The datatype dtd for schemas [2] has:

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

Shouldn't the DTD include 0 and 1?

paul

[1] http://www.w3.org/TR/xmlschema-2/#boolean
[2] http://www.w3.org/2001/datatypes.dtd