1. Entry
     Quantity Measurement Observation (2.16.840.1.113883.10.20.6.2.14)
    1. Entry
       SOP Instance Observation (2.16.840.1.113883.10.20.6.2.8)
      1. Entry
         Purpose of Reference Observation (2.16.840.1.113883.10.20.6.2.9)
      2. Entry
         Referenced Frames Observation (2.16.840.1.113883.10.20.6.2.10)
        1. Entry
           Boundary Observation (2.16.840.1.113883.10.20.6.2.11)