Mapping enumeration (multiple values) to a 1..n field

Hi Experts,

I try to pass an enumeration (with three values) to a field of type string (1..unbounded). Therefor I have created an XSD file with this three values:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>

<xsd:schema xmlns="http://XXXX.net/Reservation/Sharepoint"

  xmlns:xsd="http://www.w3.org/2001/XMLSchema" targetNamespace="http://XXXX.net/Reservation/Sharepoint">

  <xsd:complexType name="SubscribeEventTypes">

  <xsd:sequence>

  <xsd:element name="EventTypes">

  <xsd:complexType>

  <xsd:sequence>

  <xsd:element maxOccurs="unbounded" name="EventType">

  <xsd:simpleType>

  <xsd:restriction base="xsd:string">

  <xsd:enumeration value="CreatedEvent" />

  <xsd:enumeration value="ModifiedEvent" />

  <xsd:enumeration value="DeletedEvent" />

  </xsd:restriction>

  </xsd:simpleType>

  </xsd:element>

  </xsd:sequence>

  </xsd:complexType>

  </xsd:element>

  </xsd:sequence>

  </xsd:complexType>

</xsd:schema>

The XSD based on the Microsoft Web Service Interface for Exchange Server (OLX).

Another try of myself was the string-joing extraction (but did not worked for me):

string-join("CreatedEvent,ModifiedEvent,DeletedEvent",",")

Without this values, I can't start the accordant operation.

Many Thanks for help.

Cheers,

Cengiz