default value for a simpleType with restriction

Hopefully this is the right group for this question. If not please inform me
which one.

I've created a simpleType

<xs:simpleType name="dtPresentation">
  <xs:restriction base="xs:string">
    <xs:enumeration value="a" />
    <xs:enumeration value="b" />
    <xs:enumeration value="c" />
    <xs:enumeration value="d" />
    <xs:enumeration value="all" />
  </xs:restriction>
</xs:simpleType>

I would like to declare 'all' as the default value here and not where it is
being used as in

<xs:attribute name="presentation" type="dtPresentation" default="all" />

Is this possible?

Marijan (Mario) Madunic