visad/src/main/java/ucar/nc2/iosp/gempak/GempakSoundingIOSP.java
private ArraySequence makeEmptySequence(Sequence seq) {
    StructureMembers members = seq.makeStructureMembers();
    return new ArraySequence(members, new EmptyStructureDataIterator(), -1);
  }
private ArraySequence makeEmptySequence(Sequence seq) {
    StructureMembers members = seq.makeStructureMembers();
    return new ArraySequence(members, new EmptyStructureDataIterator(), -1);
  }
Create an empty ArraySequence for missing data

@param seq the Sequence variable
@return the empty sequence