dap4/d4lib/src/main/java/dap4/dap4lib/netcdf/Nc4Cursor.java
public TypeNotes
    getVlenType(DapVariable v)
    {
        DapType t = v.getBaseType();
        if(t.getSort() != DapSort.SEQUENCE
                || ((DapSequence) t).getFields().size() != 1)
            throw new IllegalArgumentException(t.getFQN());
        DapSequence ds = (DapSequence) t;
        DapVariable f0 = ds.getField(0);
        DapType f0type = f0.getBaseType();
        return (TypeNotes) ((Nc4DSP) this.dsp).find(f0type);
    }
public TypeNotes
    getVlenType(DapVariable v)
    {
        DapType t = v.getBaseType();
        if(t.getSort() != DapSort.SEQUENCE
                || ((DapSequence) t).getFields().size() != 1)
            throw new IllegalArgumentException(t.getFQN());
        DapSequence ds = (DapSequence) t;
        DapVariable f0 = ds.getField(0);
        DapType f0type = f0.getBaseType();
        return (TypeNotes) ((Nc4DSP) this.dsp).find(f0type);
    }
If the basetype is sequence (=> isVlen()),
then return the type of the first field of this sequence.
Otherwise return null.

@return the type of the first field