How do I define an element that can either contain an integer or nothing at all?

Question

The question says it all! I want to have an XSD definition that makes it either possible to create an element like this

<Element>12345</Element>

or like this

<Element></Element>

How do I do that?

I already tried using the nillable attribute and changing the element's type to xs:string but it didn't work.

Answer 1

I solved my problem creating a xs:simpleType and a xs:restriction with base xs:string concerning the xs:minLength with a value of 1.

<xs:simpleType name="type">
    <xs:restriction base="xs:string">
        <xs:minLength value="0"/>
    </xs:restriction>
 </xs:simpleType>