Scott,

The trick is in using the appropriate syntax to access the individual fields within the DICOM message.  In the example below, we're extracting data from the DICOM message to insert into a simple scheduling request message output as XML.  The same syntax can be used in reverse, writing from HL7 into DICOM.  Since the DICOM message is not fully-defined within Ensemble/HealthShare, the graphical DTL editor view is not pretty...

Hope this helps,
Mike

Class Test.Transform.DICOMToPatientSchedule Extends Ens.DataTransformDTL [ DependsOn = (EnsLib.DICOM.Document, Test.Msg.PatientScheduleReq) ]
{

Parameter IGNOREMISSINGSOURCE = 1;

Parameter REPORTERRORS = 1;

Parameter TREATEMPTYREPEATINGFIELDASNULL = 0;

XData DTL [ XMLNamespace = "http://www.intersystems.com/dtl" ]
{
<transform sourceClass='EnsLib.DICOM.Document' targetClass='Test.Msg.PatientScheduleReq' targetDocType='2.3.1:ADT_A01' create='new' language='objectscript' >
<assign value='source.GetValueAt("DataSet.PatientID")' property='target.PID' action='set' />
<assign value='"DICOM"' property='target.MessageSource' action='set' />
<assign value='source.GetValueAt("DataSet.PatientName")' property='target.PatientName' action='set' />
<assign value='source.GetValueAt("DataSet.ScheduledProcedureStepSequence[1].ScheduledProcedureStepStartDate")' property='target.ExamDateTime' action='set' />
<assign value='source.GetValueAt("DataSet.ScheduledProcedureStepSequence[1].ScheduledProcedureStepStartDate")' property='target.FileDate' action='set' />
<assign value='source.GetValueAt("DataSet.ScheduledProcedureStepSequence[1].ScheduledProcedureStepDescription")' property='target.ExamType' action='set' />
<assign value='source.GetValueAt("DataSet.AccessionNumber")' property='target.AccessionNumber' action='set' />
<assign value='source.GetValueAt("DataSet.StudyInstanceUID")' property='target.VisitId' action='set' />
<assign value='source.GetValueAt("DataSet.ScheduledProcedureStepSequence[1].ScheduledPerformingPhysicianName")' property='target.AttendingPhysician' action='set' />
</transform>
}

}