Comparison of values of anySimpleType

Hi,

I have trouble understanding how 'anySimpleType' is handled if comparing 
values. Xerces and XSV seem to differ here.

Identity-constraint example:
(using Xerces-J 2.5.1, XSV 2.5-2, MSXML 4.0)

<sequence>
   <element name="b" type="anySimpleType"/>
   <element name="c" type="float"/>
</sequence>

<b>1.0</b>
<c>1.0</c>

with the value of 'c' being a keyref to the key value of 'b'.

Results: XSV and MSXML do not find the referenced key, Xerces does.

if both types are 'float':

Results: All tree validators find the referenced key.

I cannot find a hint for 'anySimpleType' being not comparable with the
primitive types. The PER for datatypes says:

"anySimpleType is considered to have an unconstrained lexical space and 
a ·value space· consisting of the union of the ·value space·s of all the 
·primitive· datatypes and the set of all lists of all members of the 
·value space·s of all the ·primitive· datatypes."

Further "4.2.1 equal" says:

"if a datatype T' is ·derived· by ·restriction· from an atomic datatype 
T then the ·value space· of T' is a subset of the ·value space· of T. 
Values in the ·value space·s of T and T' can be compared according to 
the above rules "

Can someone explain?

Greetings,

Kasimier