spec. problem: hexBinary, base64Binary value sets disjoint and not disjoint

In the XML Schema Definition Language (XSD) 1.1 Part 2: Datatypes CR
at http://www.w3.org/TR/2009/CR-xmlschema11-2-20090430, section 2.2.3
says:

   For purposes of this specification, the value spaces of primitive
   datatypes are disjoint, even in cases where the abstractions they
   represent might be thought of as having values in common.

However, the specification goes on to define the value spaces of
hexBinary and base64Binary to be the same set of values:

Section 3.3.16.1, Value Space (for hexBinary) says:

     The ·value space· of hexBinary is the set of finite-length
     sequences of zero or more binary octets.  The length of a value
     is the number of octets.

Section 3.3.17.1, Value Space (for base64Binary) says, identically:

     The ·value space· of base64Binary is the set of finite-length
     sequences of zero or more binary octets.  The length of a value
     is the number of octets.

Since:
- the value space of hexBinary is the set of finite-length
   sequences of zero or more binary octets, and
- the value space of base64Binary is _also_ the set of finite-length
   sequences of zero or more binary octets,
then those two value spaces are the same set.  Since the are the
same set, they clearly are not disjoint.


Something needs to be adjusted in the wording.


Perhaps defining the value spaces in terms of values that correspond
to the octet sequences, but are not the octet sequences themselves,
would work.  (The values wouldn't be defined beyond corresponding
to the octet sequences and belonging to whichever value space.)

That is, saying that hexBinary's value space is a set of values
_corresponding_ to octet sequences and base64Binary's value space
is a set of values _corresponding_ to an octet sequences no longer
implies that those values are the same values and therefore that
those sets are the same set.

Daniel
-- 
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