Is it possible to define an XML schema with an arbitrary number of elements?

Here is my code so far and my question is how do I define elements within the sequence? (Each element in the sequence is also required to have attributes "name" and "Position")

<?xml version="1.0" encoding="UTF-8" ?>
<xs:schema xmlns:xs="http://ift.tt/tphNwY">
    <xs:element name="FieldData">
    <xs:complexType>
        <xs:sequence>
            <xs:element....
        </xs:sequence>
    </xs:complexType>
</xs:element>