How to Output <element xsi:nil="true"/> from a DTL Transformation in EnsLib.EDI.XML.Document?

Hi everyone,

I'm working on a DTL that transforms an HL7 message (EnsLib.HL7.Message) to an XML document (EnsLib.EDI.XML.Document).

The target XML is based on a custom schema and has an element like:

<xs:element name="deceasedDateTime" type="xs:dateTime" nillable="true"/>

What I need is for the output to show:

<deceasedDateTime xsi:nil="true"/> when the source HL7 value is empty, for eg: 

<portalPatientUpdate xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
  <deceasedDateTime xsi:nil="true" />
</portalPatientUpdate>

My questions:

1. How can I correctly assign xsi:nil="true" in the DTL transformation?
2. Where/how should I declare the xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" namespace?

Any help would be appreciated.

Thanks