If OBX3 is blank plug a 1

Question

What is the best way to have a 1 (or any value) be plugged if OBX-3 is empty?

Answer 1

This will set OBX-3 where OBX-3 is blank/empty if you only have 1 OBX Segment: 

message.setNode('OBX[@3=\'\']-3', 'abc');

Use this code if there are multiple OBX Segments:

message.setAllNodes('OBX[@3=\'\']-3', 'abc');