What are the mandatory segments in the REF I12 HL7 message?

Question

I am using NHapi(.NET, c#) terser to generate a REF I12 message with an attachment. Please help me with the following questions :

What segments are mandatory in REF I12 ?

Can an OBX segment be present in a REF message without the OBR segment ?

Answer 1

The minimal segment set for version 2.5 seems to be

MSH - Message Header
PRD - Provider Data
PID - Patient Identification

But probably you want sending more data than only the mandatory segments and none of the optional segments.

You have to provide an OBR segment, if you want to send an OBX segment.