A Doubt on defineing a simpleType in xml-schema file.

["Mariappan, MaharajanX" <m_mariappanX@trillium.com>]

Hi Folks,

I've a question on defineing a simpleType for an attribute element in
xml-schema.

Value of that type may be xsd:boolean or xsd:string or xsd:hexBinary

How can I define it?

As per my knowledge we can derive a simpleType from one of the predefined
types[44].

<xsd:simpleType name="myType">
	<xsd:choice>
		<xsd:restriction base="xsd:boolean"></xsd:restriction>
		<xsd:restriction base="xsd:string"> <xsd:length value="0"/>
</xsd:restriction>
		<xsd:restriction base="xsd:string"></xsd:restriction>
		<xsd:restriction base="xsd:hexBinary"></xsd:restriction>
	</xsd:choice>
</xsd:simpleType>

I want to define like above......but choice element cann't be within
simpleType.

...........
<xsd:attribute name="myAttribute" type="myType"/>
.......

Is there any way for above problem or I have to define only as "xsd:string"
which is superset type of remaining?

TIA,
Maharajan.